KR101775123B1 - Nitride light emitting device - Google Patents

Abstract

The present invention relates to a method of manufacturing a semiconductor device, and more particularly, to a method of manufacturing a nitride-based light emitting device. The present invention relates to a nitride semiconductor layer having a first surface and a second surface; A concavo-convex structure located on the first surface; A first electrode located on the concave-convex structure; A light extracting layer located on the second side; A second electrode located on the light extracting layer; And a protective layer located on at least one side of the nitride based semiconductor layer.

Description

[0001] NITRIDE LIGHT EMITTING DEVICE [0002]

The present invention relates to a method of manufacturing a semiconductor device, and more particularly, to a method of manufacturing a nitride-based light emitting device.

Light emitting diodes (LEDs) are well-known semiconductor light emitting devices that convert current into light. In 1962, red LEDs using GaAsP compound semiconductors were commercialized. GaP: N series green LEDs and information communication devices As a light source for a display image of an electronic device.

The wavelength of the light emitted by these LEDs depends on the semiconductor material used to fabricate the LED. This is because the wavelength of the emitted light depends on the band gap of the semiconductor material, which represents the energy difference between the valence band electrons and the conduction band electrons.

Gallium nitride semiconductors (GaN) have high thermal stability and wide bandgap (0.8 to 6.2 eV), and have attracted much attention in the field of high output electronic component development including LEDs.

One of the reasons for this is that GaN can be combined with other elements (indium (In), aluminum (Al), etc.) to produce semiconductor layers emitting green, blue and white light.

Since the emission wavelength can be controlled in this manner, it can be tailored to the characteristics of the material according to the specific device characteristics. For example, GaN can be used to create a white LED that can replace the blue LEDs and incandescent lamps that are beneficial for optical recording.

Due to the advantages of such GaN-based materials, the GaN-based LED market is rapidly growing. Therefore, GaN-based optoelectronic device technology has rapidly developed since its commercial introduction in 1994.

SUMMARY OF THE INVENTION The present invention provides a light emitting device having various structures using a nitride semiconductor thick film.

According to an aspect of the present invention, there is provided a nitride semiconductor light emitting device comprising: a nitride semiconductor layer having a first surface and a second surface; A concavo-convex structure located on the first surface; A first electrode located on the concave-convex structure; A light extracting layer located on the second side; A second electrode located on the light extracting layer; And a protective layer located on at least one side of the nitride based semiconductor layer.

The present invention has the following effects.

Firstly, the vertical nitride semiconductor light emitting diode structure is manufactured by using the nitride semiconductor thick film 20, and this structure does not require the use of a surrogate substrate.

Second, complicated processes such as wafer bonding and electroplating are removed to fabricate such a substitute substrate, thereby simplifying the fabrication process and preventing deterioration of LED characteristics caused by such complicated processes. Effect can be obtained. Also, the structural constraints are greatly reduced, and the structure of the vertical LED as described above can be diversified.

Third, since the semiconductor layer is thick by the thick film, the current can be spread evenly by its own conductivity. Therefore, it is possible to obtain a sufficient electric characteristic without applying a structure for evenly spreading the current, for example, a structure such as a CBL layer.

1 to 14 are sectional views showing an example of a manufacturing process of a light emitting device.
15 to 21 are cross-sectional views illustrating an example of the structure of a light emitting device manufactured by the manufacturing process of FIGS. 1 to 14.
22 to 27 are cross-sectional views showing another example of a manufacturing process of a light emitting device.
FIGS. 28 to 30 are cross-sectional views illustrating an example of the structure of a light emitting device manufactured by the manufacturing process of FIGS. 22 to 27. FIG.
31 and 32 are schematic diagrams showing improvement of current flow by the light emitting device structure.

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

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. Rather, the intention is not to limit the invention to the particular forms disclosed, but rather, the invention includes all modifications, equivalents and substitutions that are consistent with the spirit of the invention as defined by the claims.

It will be appreciated that when an element such as a layer, region or substrate is referred to as being present on another element "on," it may be directly on the other element or there may be an intermediate element in between .

Although the terms first, second, etc. may be used to describe various elements, components, regions, layers and / or regions, such elements, components, regions, layers and / And should not be limited by these terms.

First, thin film growth is performed for manufacturing a light emitting device.

As shown in FIG. 1, in the thin film growth, a nitride semiconductor thick film 20, which can act as a nitride semiconductor (GaN) substrate, may be formed on the growth substrate 10 first.

At this time, the growth substrate 10 may be a heterogeneous substrate such as sapphire or silicon carbide (SiC), and the thickness of the nitride semiconductor thick film 20 may be at least 50 μm or more, Lt; RTI ID = 0.0 > um. ≪ / RTI >

The nitride semiconductor thick film 20 may have n-type conductivity, but may have p-type conductivity depending on the case.

Thereafter, as shown in FIG. 2, the growth substrate 10 is separated from the nitride semiconductor thick film 20. At this time, the lift-off method may be used as the separation method, and the lift-off method may be any one of laser-assisted lift-off (LLO), lift-off using chemical etching (CLO) have.

In addition, a thermal shock method and a mechanical method for separating the thin film by itself using the strain inherent in the cooling step after the growth of the thin film can also be used.

Thereafter, as shown in FIG. 3, the nitride semiconductor thin film 30 is grown on the nitride semiconductor thick film 20. The nitride semiconductor thin film 30 may include an n-type semiconductor layer 31, an active layer 32, and a p-type semiconductor layer 33. If the thick film 20 has p-type conductivity, the positions of the n-type semiconductor layer 31 and the p-type semiconductor layer 33 may be opposite to those of Fig.

As shown in FIG. 4, the nitride semiconductor thin film 30 thus grown can be separated into individual device regions through isolation etching to separate the regions 34 to be separated into individual devices. The dry etching or the chemical etching method may be used for such a separation etching.

5, the light extracting structure 40 may be formed on the surface of the thin film 30 before performing the separation etching. The light extracting structure 40 may have a surface roughness, Photoelectrolytic etching, a nitride semiconductor island, and a photonic crystal.

In this case, the surface on which the light extracting structure 40 is formed may be the outer surface of the p-type semiconductor layer 33.

Unlike the above process, the nitride semiconductor thin film 30 can be formed continuously after the growth of the nitride semiconductor thick film 20 without separating the growth substrate 10, and the nitride semiconductor thin film 30 30), the growth substrate 10 may be separated.

The separation of the growth substrate 10, the nitride semiconductor thick film 20, the nitride semiconductor thin film 30, and the growth substrate 10 may be the same as described above.

6, a p-type electrode structure 50 is fabricated on the nitride semiconductor thin film 30. First, a transparent conductive layer 51 is formed on a thin film 30 divided into individual element isolation regions. And the p-electrode 52 can be formed on the transparent conductive layer 51.

At this time, the transparent conductive layer 51 and the p-electrode 52 may be patterned on the thin film 30 divided into individual device regions. The transparent conductive layer 51 may be a transparent conductive oxide.

As shown in FIG. 7, a light extracting pattern 53 may be formed on the transparent conductive layer 51 as the case may be.

8, a protective layer 60 may be formed to surround the periphery of the p-type electrode structure 50 and at least a part of the nitride semiconductor thin film 30.

8, the protective layer 60 may be formed to surround both the upper surface of the semiconductor thin film 30 except the p-type electrode structure 50 and the side surface of the thin film 30, Or may be located only on the upper surface or the side surface of the semiconductor thin film 30. It may also be located on a part of the upper surface or only a part of the side surface of the semiconductor thin film 30.

The protective layer 60 may be made of at least one of SiO ₂ , SiN _x , and SiON _x . The protective layer 60 may serve as a passivation layer to protect the outer surface of the semiconductor thin film 30 and prevent damage to the thin film 30 due to static electricity.

Thereafter, as shown in FIG. 9, an n-type electrode structure 70 is formed on the rear surface of the nitride semiconductor thick film 20. Prior to forming the n-type electrode structure 70, the thick film 20 can be thinned to an appropriate thickness by a lapping process, and in addition, a step of polishing the lapped surface May be added.

This polishing process has the meaning of forming a suitable surface to form a rigid n-type electrode structure 70 with low resistance.

The n-type electrode structure 70 may be an n-type reflective electrode 71 as shown in FIG. 9 and may be a transparent electrode 72 and an n-type electrode 73 as shown in FIG. 10, And may be composed of only the n-type electrode 73 as shown in Fig.

In this case, when the transparent electrode 72 and the n-type electrode 73 are formed as shown in FIG. 10, the light extracting pattern 74 may be formed on the transparent electrode 72 as shown in FIG.

Here, the transparent electrode 72 may be made of a transparent conductive oxide, and in some cases, a very thin metal layer may be used.

On the other hand, the lower surface of the nitride semiconductor thick film 20 forming the n-type electrode structure 70 is a surface on which the above-described growth substrate 10 is separated, and this surface can be a nitrogen face (N face).

That is, the outer surface of the nitride semiconductor structure may have a polar face, and the polar face forms a Ga-polar face or an N-polar face.

In forming the n-type electrode structure 70 on the nitrogen polarity surface, as shown in Fig. 13, the irregular structure 21 for improving the ohmic contact structure can be formed. That is, the n-type electrode structure 70 can be formed on the surface on which the concave-convex structure 21 is formed.

The concavoconvex structure 21 is formed on the lower surface of the thick film 20, and may have a random structure, and may have a plurality of unit shapes, as the case may be.

At this time, the unit shape may be a conical shape, a polygonal column, a stripe shape, or the like, and may have various shapes (not shown) such as a polygonal column and a stripe-shaped triangular column whose upper width is narrower than the lower width .

The size of the concavo-convex structure 21 may be 3 탆 to 6 탆, and the side inclination angle of the concavo-convex structure may be 45 째 to 80 째.

In some cases, a nano pillar structure may be further formed on the concave-convex structure 21 (not shown).

As described above, when the concave-convex structure 21 is formed on the N-polar face of the nitride semiconductor thick film 20, the relative area of the nitrogen polar face, which has relatively poor ohmic characteristics, It is possible to provide a low contact resistance and improve the heat radiation characteristic.

The concave and convex structure 21 can be formed by patterning using a photomask and can be formed by ICP-RIE (Inductively Coupled Plasma-Reactive Ion Etching), ECR-RIE (Electron Cyclotron Resonance-Reactive Ion Etching) Beam Etching, and Helicon Plasma Etching. As the mask used herein, SiO ₂ , a photoresist, a metal, or the like can be used.

In forming the concave and convex structure 21, wet etching using a solution of KOH, H ₃ PO _4, or the like after dry etching may cause the characteristics of the n-type electrode structure 70 formed on the concavo- Can be further improved.

On the other hand, the size of the concave-convex structure 21 may have a size of several micrometers, and may have a size of about 3 to 5 micrometers.

One of the reasons is that when the side inclination angle of the concave and convex structure 21 is 45 DEG or less, the relative area of the nitrogen polar face is sufficiently large It may not be easy to obtain a desired level of ohmic characteristics because it is not small. If the side inclination angle of the concavo-convex structure is 80 degrees or more, it may become difficult to form the n-type electrode structure 70 thereafter.

The lateral inclination angle of the concave and convex structure 21 can be adjusted by changing the etching conditions. For example, in the case of dry etching, the side inclination angle of the concave and convex structure 21 can be adjusted by controlling the plasma power and the etching gas.

In addition, the side inclination angle of the concavoconvex structure 21 may affect the heat radiation characteristics of the entire device.

On the other hand, the concavoconvex structure 21 may be formed by applying the nanoparticles to the nitrogen polar surface (rear surface) of the nitride semiconductor thick film 20, and then etching the nitrogen polar surface using the nanoparticles as a mask.

According to this, a nano pillar-shaped concave-convex structure having a size of several micrometers to several nanometers can be formed according to the size of the nanoparticles. In this case, the size of the nanofiller can be 10 to 1000 nm.

In addition, such a nanofiller can be formed on the concavo-convex structure 21 formed by patterning using a photomask and dry etching.

That is, after forming the concave-convex structure 21 by patterning using a photomask and dry etching method on the nitrogen polarity surface, the nanopillar can be formed on the concave-convex structure 21 by applying and etching the concave-convex structure 21, The ohmic characteristic and the heat dissipation characteristic can be further improved.

After the lower n-type electrode structure 70 is formed as described above, it is separated into individual elements according to the individual element isolation regions 34 as shown in Fig. 14, the n-type electrode structure 70 has a structure as shown in FIG. 9. However, it is needless to say that the n-type electrode structure 70 may have various structures as described above.

The individual element isolation process may be performed by separating the nitride semiconductor thick film 20, and may be performed by a scribing and / or braking process.

The scribing process can be performed using a laser or etching. The element may be completely separated by such a scribing process, and in some cases, the scribing process and the braking process may be performed together. That is, after performing scribing in the element isolation region, braking may be performed along the scribed direction.

Individual devices are fabricated by such a process.

In the meantime, unlike the above-described process, the order of the separation process of the substrate 10 may be different. That is, as described above, after the growth of the thick film 20 or the growth of the thin film 30 on the thick film 20, the growth substrate 10 is not separated and the formation of the p-type electrode structure 40, The growth substrate 10 may be separated.

The other process may be the same as described above.

An example of a light emitting device that can be manufactured by the above process will be described below. Although the element structure described here is shown as having a concave-convex structure 21 on the lower surface of the nitride semiconductor thick film 20, it is needless to say that such concave-convex structure 21 may be omitted in some cases.

Such a device structure can be variously combined with the above-described features. That is, the nitride semiconductor thin film 20, the nitride semiconductor thin film 30, the light extracting structure 40, the p-type electrode structure 50, the protective layer 60, and the n-type electrode structure 70 Each feature can be combined in various ways to achieve a device structure. Here are some examples:

First, the structure as shown in FIG. 14 described above can be structured as shown in FIG. 15 in more detail.

15, if the nitride semiconductor thin film 30 has a light extracting structure 40 formed thereon, the structure of FIG. 16 can be obtained. That is, the light extracting structure 40 is positioned on the p-type semiconductor layer 33 of the thin film 30 and the transparent conductive layer 51 and the p- A p-type electrode structure 50 composed of the electrode 52 can be located.

Although the nitride semiconductor thick film 20 and the n-type semiconductor layer 31 of the nitride semiconductor thin film 30 are shown separately, they may be viewed as one n-type semiconductor structure. This is because the electrical properties of the material are almost identical. This can also be applied in common to all example device structures described herein.

17 and 18 show other examples in a state in which the light extracting structure 40 is located in the nitride semiconductor thin film 30. In FIG.

In Fig. 17, the structure is substantially similar to that of Fig. 16, except that the n-type electrode structure 70 has the transparent electrode 72 and the n-type electrode 73 as described with reference to Fig. That is, the same structure as the structure of FIG. 16 is shown except for the n-type electrode structure 70.

18 shows a structure in which the p-type electrode 52 is located on the light extracting structure 40 and the n-type electrode structure 70 is located on the concave and convex structure 21 of the nitride semiconductor thick film 20 An example of a device is shown. Other parts which are not described may be the same as the other examples.

In Fig. 19, the same structure as that of Fig. 15 is shown except that the n-type electrode structure 70 has the transparent electrode 72 and the n-type electrode 73. Fig.

On the other hand, FIG. 20 shows an example in which the transparent conductive layer 51 has the light extracting pattern 53 as described with reference to FIG. That is, the case where the p-type electrode structure 50 has the transparent conductive layer 51 and the p-type electrode 52 having the light extracting pattern 53 is described, same.

21, the p-type electrode structure 50 is composed of the transparent conductive layer 51 having the light extracting pattern 53 and the p-type electrode 52, and the n- And the transparent electrode 72 and the n-type electrode 73 each having the transparent electrode 74 are shown.

In the example shown in Figs. 17 to 19 and 21, light generated at the light emitting element driving can be emitted in the direction of the n-type semiconductor layer 31, that is, in the direction toward the nitride semiconductor thick film 20.

In this case, both light emitted in both directions may be used, and in some cases, the device may be packaged while being rotated by 90 degrees in the state shown in the figure.

Hereinafter, a structure in which the n < - > -type semiconductor layer 31 is directed upward and a manufacturing method thereof will be described, unlike the structure described above.

The process of growing the nitride semiconductor thick film 20 on the growth substrate 10 and then growing the semiconductor thin film 30 after the growth substrate 10 is separated is the same as the process of FIGS. Do.

Thereafter, as shown in Fig. 22, a p-type reflective electrode 54 is formed on the p-type semiconductor layer 33 of the semiconductor thin film 30. Then, as shown in Fig. The p-type reflective electrode 54 may serve as a contact layer with the p-type semiconductor layer 33 and a reflective electrode, or may be a combination of a contact layer made of a different layer and a reflective electrode.

A p-type electrode 55 is formed on the p-type reflective electrode 54 as shown in Fig. 23, and a protective layer 60 is formed on the exposed portion of the semiconductor thin film 30. The protective layer 60 may be the same as described above.

24, a light extracting structure 22 can be formed on the lower surface of the nitride semiconductor thick film 20, and an n-type electrode 76 is formed on the surface on which the light extracting structure 22 is formed The n-type electrode structure 70 can be formed.

25, an n-type transparent electrode 75 is formed on the lower surface of the nitride semiconductor thick film 20 on which the light extracting structure 22 is formed, and n -Type electrode 76 may be formed to form the n-type electrode structure 70.

26, after the n-type transparent electrode 75 is formed on the lower surface of the nitride semiconductor thick film 20 without forming the light extracting structure, the n-type transparent electrode 75 is formed on the n- The light extracting structure 77 may be formed on the transparent electrode 75 of FIG. The n-type electrode 76 is formed on the n-type transparent electrode 75 on which the light extracting structure 77 is formed.

Each structure can then be separated into individual elements depending on the individual element isolation regions.

Fig. 28 shows a device structure in a state in which the upper and lower positions are reversed and separated into individual devices in the structure shown in Fig. 24 described above. That is, the light extracting structure 22 is located on the upper side of the nitride semiconductor thick film 20, the n-type electrode 76 is located on the side where the light extracting structure 22 is located, A p-type electrode structure 50 composed of a p-type reflective electrode 54 and a p-type electrode 55 is located.

Here, the protective layer 60 covers the nitride semiconductor thin film 60, but may be formed so as to cover part of the nitride semiconductor thick film 20 as the case may be.

Other portions can be applied as described above.

FIG. 29 shows a device structure in which the structure as shown in FIG. 25 is separated into individual devices and the up and down positions are reversed. Fig. 30 shows a device structure in which the structure described in Fig. 27 is separated into individual devices and the top and bottom positions are reversed. The matters for each component may be the same as described above.

The light emitting device described above includes the content of fabricating the vertical type light emitting diode structure by using the nitride semiconductor thick film 20, and such structure does not require the use of a surrogate substrate.

Therefore, complicated processes such as wafer bonding and electroplating for fabricating such a surrogate substrate are eliminated to simplify the fabrication process and to prevent deterioration of LED characteristics caused by such complicated fabrication processes Effect can be obtained. Also, the structural constraints are greatly reduced, and the structure of the vertical LED as described above can be diversified.

Techniques and equipment for thick and stable growth of high-quality thin films are evolving day by day. The most representative method is Hydride Vapor Phase Epitaxy (HVPE). Recently, however, techniques for thickening a high-quality thin film using LPE (Liquid Phase Epitaxy) and MOCVD (Metalorganic Chemical Vapor Epitaxy) have been disclosed.

By using such a method, a thick nitride semiconductor thick film having a thickness of 50 μm or more is grown on a growth substrate such as sapphire or silicon carbide (SiC), and then only the substrate is separated. Handling is possible.

Using such a thick semiconductor thin film (thick film) feature, the vertical LED process can be greatly simplified as described above. First, since a surrogate substrate is not necessary, a process for providing a surrogate substrate becomes unnecessary, and various problems caused therefrom are also eliminated.

Further, since the semiconductor film is thick due to the thick film, the current can be evenly spread by its own conductivity, as shown in Figs. Therefore, it is possible to obtain a sufficient electric characteristic without applying a structure for evenly spreading the current, for example, a structure such as a CBL layer.

On the other hand, in the structure using a surrogate substrate, a reflective electrode is formed on the p-type semiconductor layer surface and light is extracted through the surface of the opposite n-type semiconductor layer in order to prevent light absorption in the surrogate substrate. Thick film-based technology, various vertical LED structures as described above can be implemented.

10: growth substrate 20: nitride semiconductor thick film
30: nitride semiconductor thin film 40: light extracting structure
50: p-type electrode structure 60: protective layer
70: n-type electrode structure

Claims (18)

A nitride semiconductor thick film having a first face which is a nitrogen polar face, a second face which is a gallium polar face, and which has a thickness of 50 to 300 mu m;
A concavo-convex structure located on the first polar side of the nitrogen surface and having a side inclination angle of 45 ° to 80 °;
A nitride semiconductor thin film disposed on the second surface;
A first electrode located on the concave-convex structure and serving as a reflective electrode;
A light extraction layer located on the nitride semiconductor thin film;
A second electrode located on the light extracting layer; And
And a protective layer located on at least one side of the nitride semiconductor thin film. The nitride based light emitting device according to claim 1, wherein the light extracting layer is a light extracting structure that is a part of the nitride semiconductor thin film. The nitride based light emitting device according to claim 1, wherein the light extracting layer is a transparent conductive layer. The nitride based light emitting device according to claim 1, wherein the light extracting layer is a transparent conductive layer having a light extracting structure. The nitride-based light emitting device according to claim 1, wherein the first electrode is a reflective electrode contacting the concave-convex structure. delete delete The nitride-based light emitting device according to claim 1, wherein the convexo-concave structure is a nitride-based light emitting device for improving ohmic contact characteristics of the first electrode. The nitride-based light emitting device according to claim 1, wherein the concave-convex structure is any one of a conical shape, a polygonal column with an upper width smaller than a lower width, and a triangular column with a stripe shape. The nitride-based light emitting device according to claim 1, wherein the size of the unit shape constituting the concavo-convex structure is 3 탆 to 6 탆. delete The nitride based light emitting device according to claim 1, wherein a fine pillar structure is located on the uneven structure. 13. The nitride based light emitting device according to claim 12, wherein the fine pillar structure is nanoscale. The nitride based light emitting device according to claim 1, wherein the protective layer is at least one of SiO ₂ , SiN _x , and SiON _x . The nitride-based light emitting device according to claim 1, wherein the nitride semiconductor thick film functions as a substrate. delete The nitride based light emitting device according to claim 1, wherein the nitride semiconductor thin film includes a first conductive semiconductor layer, an active layer, and a second conductive semiconductor layer. delete

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