KR101475509B1 - Light emitting device and method for manufacturing thereof - Google Patents

Abstract

The present invention relates to a semiconductor light emitting device and a manufacturing method thereof. A method of manufacturing a semiconductor light emitting device according to the present invention includes the steps of: providing a substrate on which at least one via hole is formed; forming a sacrificial layer on the substrate; forming a semiconductor light emitting device on the sacrificial layer; And wet etching the sacrificial layer to separate the substrate from the semiconductor light emitting device, wherein the etchant penetrates the side surface of the sacrificial layer and at least one via hole to wet etch the sacrificial layer.

Sapphire, Light Emitting Diode, Via Hole, Etch

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a light emitting device,

The present invention relates to a light emitting device, in particular, a nitride semiconductor light emitting device and a method of manufacturing the same.

2. Description of the Related Art Semiconductor light emitting devices such as light emitting diodes (LEDs) have a long lifespan and low power consumption, and are widely used not only in the fields of electricity and electronics, but also in advertising. Recently, attempts have been actively made to use, for example, an LED as a backlight unit of a liquid crystal display device. In addition, LED is expected to be widely used in everyday life as indoor lighting in the future.

FIGS. 1A to 1E are views schematically showing a manufacturing process of a conventional nitride semiconductor light emitting device.

1A, a buffer layer 111 and an n-type nitride layer 113 are formed by a method such as MOCVD (Metal Organic Chemical Vapor Deposition) as shown in FIG. 1B after a sapphire substrate is provided as a substrate 101, ), An active layer 115 and a p-type nitride layer 117 are formed. The buffer layer 111 prevents cracks from being generated due to a difference in lattice constant and thermal expansion coefficient between a heterogeneous substrate (for example, a sapphire substrate) and a semiconductor layer. That is, the buffer layer 111 improves the quality of the light emitting device by reducing the crystal defects of the semiconductor layer due to the difference in physical characteristics between the semiconductor layer material to be grown later and the substrate. In the case of the nitride semiconductor layer, the buffer layer 111 is usually made of GaN or AlN .

Subsequently, a bonding layer 119 and a submount 121 are formed on the p-type nitride layer 117, as shown in FIG. The bonding layer 119 includes a p-type contact corresponding to the p-type nitride layer 117, a mirror for extracting light generated in the active layer downward, and a submount bonding layer for bonding to the submount 121. [ (P-type contact, mirror and submount bonding layer are not shown). The submount 121 may be formed of a plurality of structures in place of the substrate 101 so that a plurality of structures can be handled without disassembly in performing a wafer unit type process even after the substrate 101 is removed. Serves as an auxiliary substrate for supporting and an electrode for supplying a carrier to the semiconductor element.

1D, when the laser light 131 is irradiated to the bottom surface of the substrate 101, in particular, the sapphire substrate, the irradiated laser light 131 is incident on the sapphire substrate 101 and the nitride semiconductor layer, And is absorbed by the buffer layer 111, which is the interface of the layer 111. 1E, when the irradiated laser light 131 is absorbed in the buffer layer 111, Ga and N are separated from the buffer layer 111, which is GaN, for example. When the laser light 131 having a low melting point is melted or acid acid to separate the sapphire substrate 101 from the semiconductor device. The method of separating the substrate 101 in this manner is called a laser lift off (LLO).

In the method of separating a substrate by the conventional laser lift-off, expensive equipment for generating laser light is required, which causes a problem that the process cost is excessively increased. Further, in the conventional method of separating a substrate by laser lift-off, there is a problem that a process time is excessively required for irradiating a laser beam onto a large area substrate. Further, in the method of separating the substrate by the conventional laser lift-off, since the area irradiated with the laser at a limited time is narrowed and the buffer layer of the portion not irradiated with the laser is kept in contact with the substrate, Cracks are generated between the buffer layer and the buffer layer remaining on the substrate due to stress.

The present invention provides a semiconductor light emitting device capable of separating a substrate by a chemical (wet / chemical etching) lift-off and a method of manufacturing the same.

It is another object of the present invention to provide a semiconductor light emitting device capable of easily separating a substrate by penetrating an etching solution into at least one via hole and a method of manufacturing the same.

Another object of the present invention is to provide a semiconductor light emitting device and a method of manufacturing the same, which can separate the substrate by allowing the etchant to penetrate more easily by chamfer portions formed in the via holes.

It is still another object of the present invention to provide a semiconductor light emitting device using a sacrificial layer which is easily etched into an etching solution as well as an excellent semiconductor crystal, and a method of manufacturing the same.

It is still another object of the present invention to provide a semiconductor light emitting device using a low-temperature buffer layer and a method of manufacturing the semiconductor light emitting device so that a semiconductor layer can be effectively grown when high-temperature processing conditions are applied.

According to one aspect of the present invention, there is provided a method of manufacturing a semiconductor light emitting device, including: providing a substrate on which at least one via hole is formed; forming a sacrificial layer on the substrate; Forming a device and wet etching the sacrificial layer by providing an etchant to separate the substrate from the semiconductor light emitting device, wherein the etchant penetrates into the side surface of the sacrificial layer and the at least one via hole, Layer is wet-etched.

In a preferred embodiment, the substrate is a sapphire substrate. And the semiconductor light emitting element is a nitride light emitting element.

The sacrificial layer is a ZnO layer. Further, the ZnO layer is characterized by Zn _x Mg _1-x O (0 < x? ₁ ) or Zn _y Cd _1-y O (0 <y? 1).

Further, the method may further include forming a low-temperature buffer layer on the sacrificial layer, wherein the semiconductor light-emitting device is formed on the low-temperature buffer layer.

Further, the low-temperature buffer layer is characterized by being Al _x Ga _y In _1-xy N (o? _{X? 1} , 0? Y? 1).

The method may further include forming a bonding layer and a submount sequentially on the semiconductor light emitting device, wherein the submount is a conductive substrate.

The semiconductor light emitting device may include a first semiconductor layer, an active layer, and a second semiconductor layer.

Each of the at least one via hole has a chamfered portion formed on an upper portion adjacent to the semiconductor light emitting device.

According to another aspect of the present invention, a semiconductor light emitting device manufactured by the above-described method can be provided.
According to another aspect of the present invention, a method of manufacturing a semiconductor light emitting device includes: providing a substrate; Forming a sacrificial layer on the substrate; Forming a semiconductor layer on the sacrificial layer; Forming a submount on the semiconductor layer; Forming at least one via hole in the substrate; Wet etching the sacrificial layer with an etchant to separate the substrate from the semiconductor layer, the etchant may be wet etched through the side surface of the sacrificial layer and the at least one via hole to wet the sacrificial layer .

According to the present invention, the present invention can provide a semiconductor light emitting device and a method of manufacturing the same, which can reduce the process cost and process time by separating the substrate by chemical lift-off.

According to the present invention, it is possible to provide a semiconductor light emitting device capable of easily separating a substrate by penetrating an etching solution into at least one via hole, and a method of manufacturing the same.

According to the present invention, it is possible to provide a semiconductor light emitting device and a method of manufacturing the semiconductor light emitting device, which can separate the substrate easily by penetrating the etchant by the chamfered portions formed in the respective via holes.

According to the present invention, it is possible to provide a semiconductor light emitting device using a sacrificial layer which can not only grow excellent semiconductor crystals but also easily etch the etchant, and a method for manufacturing the same.

According to the present invention, a semiconductor light emitting device using a low-temperature buffer layer and a method of manufacturing the semiconductor light emitting device can be provided so that a semiconductor layer can be effectively grown when high-temperature process conditions are applied.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings.

FIGS. 2A to 2E are schematic views illustrating a process of manufacturing a semiconductor light emitting device according to a preferred embodiment of the present invention.

First, as shown in FIG. 2A, a plurality of via holes 203 are formed in the substrate 201. The substrate 201 according to the present invention is a sapphire substrate. The process of forming the via hole 203 may be roughly performed by wet etching using high temperature sulfuric acid and nitric acid or dry etching using a high density plasma to a previously prepared sapphire substrate 201, A via hole 203 may be formed to penetrate the upper surface and the lower surface of the substrate 201. The number of the via holes 203 may be one, but a plurality is preferable. The wet etching method and the dry etching method for the sapphire substrate 201 are well known, and therefore, a detailed description thereof will be omitted.

Then, as shown in FIG. 2B, a sacrifice layer 205 is formed on the sapphire substrate 201 having the via hole 203 formed therein. As the sacrificial layer 205, ZnO single crystals can be used. The ZnO single crystal has a lattice constant of 2.2% with a nitride semiconductor, particularly GaN. In addition, in the ZnO single crystal used as the sacrificial layer 205, epitaxial growth of the nitride semiconductor can be easily performed as a wurzite structure similar to that of GaN, and can be easily removed by conventional wet etching, It is easy to carry out the separation process. It is preferable that the ZnO layer used as the sacrificial layer 205 is Zn _x Mg _1-x O (0 <x? ₁ ) or Zn _y Cd _1-y O (0 <y? 1).

The sacrificial layer 205 grown on the sapphire substrate 201 on which the via hole 203 is formed becomes capable of epitaxial lateral overgrowth (ELO) by a via hole, thereby reducing the dislocation density in the grown sacrificial layer , The nitride semiconductor layer grown using the sacrifice layer having the low dislocation density as a buffer layer also has a low dislocation density, which enables a high-quality thin film growth. More specifically, the sacrifice layer 205, which is a low-dislocation density buffer layer, is first grown on the sapphire substrate 201 on which at least one via hole 203 is formed by a single crystal growth of a ZnO layer . In this case, the growth of the ZnO layer, which is the sacrifice layer 205, progresses at a portion where the via hole 203 is not formed in the sapphire substrate 201 in the beginning. When the grown ZnO crystals are grown in the horizontal direction, the ZnO crystals are laterally grown to meet with each other at the middle portion of the via hole 203. Gaps or cracks exist in the crystal in the portion where the intermediate portion on the via hole 203 is met. When the single crystal growth is proceeded in this state, crystal growth progresses in the vertical direction to form thick crystals, gaps or cracks disappear, and a high-quality thin film is formed because the potential does not propagate in the vertical direction. A ZnO layer as a sacrifice layer 205 is grown in a lateral direction on the sapphire substrate 201 having via holes 203 according to the above-described method to form a low dislocation density buffer layer.

2C, a low-temperature buffer layer 211, an n-type nitride layer 213, an active layer 215, and a p-type nitride layer 217 are sequentially formed on the sacrificial layer 205. It is preferable that the low-temperature buffer layer 211 is formed on the sacrifice layer 205 because the ZnO used as the sacrifice layer 205 is thermally chemically very unstable and easily decomposed at a relatively low temperature (about 500 ° C). The low-temperature buffer layer 211, particularly the low-temperature nitride buffer layer, is preferably Al _x Ga _y In _1-xy N (o? _{X? 1} , 0? Y? In the preferred embodiment of the present invention, since the nitride crystal grows on the low-temperature buffer layer 211, the ZnO layer as the sacrifice layer 205 does not need to form a complete single crystal. In the preferred embodiment of the present invention, even if the ZnO layer, which is the sacrifice layer 205, is partially exposed when exposed to high temperature conditions, the growth of the nitride single crystal formed on the low-temperature buffer layer 211 is not affected.

In another embodiment of the present invention, the n-type nitride layer 213, the active layer 215 and the p-type nitride layer 217 are formed in this order in the state where the low-temperature buffer layer 211 is not formed on the sacrifice layer 205 It can be formed later. That is, the low-temperature buffer layer 211 is an optional component.

Subsequently, as shown in FIG. 2D, a bonding layer 219 and a submount 221 are sequentially formed on the nitride semiconductor layer. The bonding layer 219 includes a p-type contact corresponding to the p-type nitride layer 217, a mirror for extracting light generated in the active layer downward, and a submount bonding layer for bonding to the submount 221. (P-type contact, mirror and submount bonding layer are not shown). The submount 221 may be formed of a plurality of structures in place of the substrate 201 so that a plurality of structures can be handled without being disassembled in performing a wafer unit type process even after the substrate 201 is removed. And serves as a supporting substrate and an electrode. The submount 221 is preferably made of a conductive material such as Si or metal.

Next, as shown in FIG. 2E, the ZnO layer, which is the sacrifice layer 205, is etched by wet etching to separate the semiconductor light emitting device and the substrate 201 from each other. The ZnO layer used as the sacrificial layer 205 is thermally chemically very unstable and easily etched into the etchant. The substrate 201 is easily separated from the semiconductor light emitting device by the chemical lift off (CLO) .

3A and 3B are views schematically illustrating the role of a via hole according to a preferred embodiment of the present invention.

3A, a ZnO layer as a sacrifice layer 205 and a semiconductor light emitting device 250 are formed on a substrate 201 on which at least one via hole 203 is formed. 3B, the etchant etches the sacrificial layer 205 through the at least one via hole 203 and the side surface of the sacrificial layer 205 (see the arrows shown in FIG. 3B 271) indicates the direction of penetration of the etching solution.

In the case where at least one via hole 203 is not formed in the substrate 201, since the etchant penetrates only to the side surface of the sacrificial layer 205, the etched portion is very narrow and most of the sacrificial layer 205 (The center portion of the layer 205) is not etched, it is very difficult to separate from the semiconductor light emitting element. In contrast, the substrate 201 according to the present invention is formed with at least one via hole 203, so that the etchant is not only formed on the side surface of the sacrificial layer 205, but also on at least one via hole The etching efficiency can be greatly increased since the semiconductor layer 203 penetrates the sacrificial layer 205 and is etched. As a result, the substrate 201 can be easily separated from the semiconductor light emitting device by the chemical lift-off method.

4A and 4B are schematic views illustrating the role of a chamfered via hole according to another preferred embodiment of the present invention.

4A, a ZnO layer, which is a sacrifice layer 205, and a semiconductor light emitting device 250 are formed on a substrate 201 on which at least one via hole 203 is formed. A chamfered portion 209 is formed on each of the via holes 203. The chamfered portion 209 is formed by chamfering the top of the via hole 203, that is, the entrance of the via hole 203 on the side where the semiconductor layer is grown, with the via hole 203 formed in the substrate 201. 4B, the etchant etches the sacrificial layer 205 through the at least one via hole 203 and the side surface of the sacrificial layer 205 (see arrow 273 (see FIG. 4B) ) Refers to the direction of penetration of the etchant. The etchant penetrating through the via hole 203 can more easily etch the sacrificial layer 205 due to the presence of the chamfered portion 209. [

After the substrate 201 is separated by chemical lift-off (CLO) as shown in FIGS. 3A and 3B or FIGS. 4A and 4B, the low-temperature buffer layer according to a preferred embodiment of the present invention is formed by dry etching Can be removed. Through the above-described process, the semiconductor light emitting device can be completed.

It is needless to say that the present invention is not limited to the above-described embodiment, and many modifications may be made by those skilled in the art within the scope of the present invention.

FIGS. 1A to 1E are views schematically showing a manufacturing process of a conventional nitride semiconductor light emitting device.

FIGS. 2A to 2E are schematic views illustrating a method of manufacturing a semiconductor light emitting device according to a preferred embodiment of the present invention.

3A and 3B are views schematically illustrating the role of a via hole according to a preferred embodiment of the present invention.

4A and 4B are views schematically illustrating the role of a chamfered via hole according to another preferred embodiment of the present invention.

Claims (12)

Providing a substrate on which at least one via hole is formed; Forming a sacrificial layer on the substrate; Forming a semiconductor layer on the sacrificial layer; And Wet etching the sacrificial layer to provide an etchant to separate the substrate from the semiconductor layer, wherein the etchant penetrates into the side surface of the sacrificial layer and the at least one via hole to wet etch the sacrificial layer and, Wherein each of the at least one via hole has a chamfered portion formed on an upper portion adjacent to the semiconductor layer. The method according to claim 1, Wherein the substrate is a sapphire substrate. The method of claim 2, Wherein the semiconductor layer is a nitride semiconductor layer. The method according to claim 1, Wherein the sacrificial layer is a ZnO layer. The method of claim 4, Wherein the ZnO layer is Zn _x Mg _1-x O (0 <x? ₁ ) or Zn _y Cd _1-y O (0 <y? 1). The method of claim 4, Further comprising forming a low-temperature buffer layer on the sacrificial layer, Wherein the semiconductor layer is formed on the low-temperature buffer layer. The method of claim 6, Wherein the low-temperature buffer layer is made of Al _x Ga _y In _1-xy N (0? X? 1, 0? _Y? 1). The method according to claim 1, Further comprising sequentially forming a bonding layer and a submount on the semiconductor layer, Wherein the submount is a conductive substrate. The method according to claim 1, Wherein the semiconductor layer includes a first semiconductor layer, an active layer, and a second semiconductor layer. delete delete delete

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