KR20090018451A - Vertically structured gan type light emitting diode device and method for manufacturing the same - Google Patents

Abstract

A method for manufacturing a vertically structured GaN type LED device is provided to form a trench inside an n type nitride GaN layer in a dry etching process without analyzing an amount of etching through different etching rate of the n type nitride GaN layer and an etching stop layer. A first n type nitride GaN layer(121a) is formed on a substrate. An etching stop layer(200) is formed on the first n-type nitride GaN layer. A second n type nitride GaN layer(121b) is formed on the etching stop layer. An active layer(122) and a p type nitride GaN layer(123) are successively formed on the second n type nitride GaN layer. A P electrode(130) is formed on the p-type nitride GaN layer. A structure support layer(150) is formed on the p type electrode. The substrate is removed. The first n type nitride GaN layer is exposed. The exposed first n type nitride GaN layer is wet-etched. An unevenness pattern(160) is formed. The first n type nitride GaN layer and an etching stop layer are dry-etched. A part of the second n-type nitride GaN layer is exposed. An n type electrode(180) is formed on the exposed second n type nitride GaN layer.

Description

Vertically structured GaN type Light Emitting Diode device and method for manufacturing the same

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vertical structure (vertical electrode) gallium nitride based (GaN) light emitting diode (LED) device and a method of manufacturing the same. It relates to a method of manufacturing a vertical structure gallium nitride-based LED device having a surface irregularities.

In general, gallium nitride-based LED devices grow on sapphire substrates, but these sapphire substrates are hard, electrically nonconducting, and have poor thermal conductivity, which reduces the size of gallium nitride-based LED devices, thereby reducing manufacturing costs, or reducing light output and chip characteristics. There was a limit to the improvement. In particular, in order to increase the output power of the LED device is required to apply a large current, it is very important to solve the heat emission problem of the LED device.

As a means to solve this problem, a vertically structured gallium nitride based LED device in which a sapphire substrate is removed by a laser lift-off (LLO) technique has been proposed.

Next, a method of manufacturing a conventional vertical gallium nitride based LED device will be described in detail with reference to FIGS. 1A to 1G.

1A through 1G are cross-sectional views sequentially illustrating a method of manufacturing a vertical gallium nitride based LED device according to the prior art.

First, as shown in FIG. 1A, a light emitting structure 120 made of a gallium nitride based semiconductor layer is formed on a sapphire substrate 110. In this case, the light emitting structure 120 has a multilayer structure in which an n-type gallium nitride layer 121, an active layer 122, and a p-type gallium nitride layer 123 are sequentially stacked from the surface of the sapphire substrate 110.

Subsequently, as shown in FIG. 1B, a p-type electrode 130 is formed on the p-type gallium nitride layer 123, and then a structural support layer 150 is formed on the p-type electrode 130.

Thereafter, as shown in FIG. 1C, the sapphire substrate 110 is removed through an LLO process.

Subsequently, as shown in FIG. 1D, a portion of the surface of the n-type gallium nitride layer 121 separated and exposed from the sapphire substrate (not shown) is wet-etched to form a surface of the n-type gallium nitride layer 121. The uneven pattern 160 is formed.

Next, as shown in FIG. 1E, a portion of the surface of the n-type gallium nitride layer 121 on which the uneven pattern 160 is formed is dry-etched to a predetermined depth to define the trench 170 defining the n-type electrode formation region. Form.

Subsequently, as illustrated in FIG. 1F, a conductive material is deposited on the trench 170 formed in the n-type gallium nitride layer 121 to form an n-type electrode 180.

However, when the concave-convex pattern 160 is formed by a wet etching process, since the etch rate is high in the case of the n-type gallium nitride layer 121, n-type nitride is formed as shown in “A” of FIG. 1E. Since the gallium layer 121 is over-etched, a portion of the active layer 122 positioned below is damaged.

In addition, conventionally, in order to control the depth of the trench 170, there is a problem in the process, such as having to check the signal indicating the change in the etching amount through a controller that performs a separate end point detector (EPD) function from time to time .

As described above, when manufacturing the vertical gallium nitride-based LED device according to the prior art, there is a problem that the characteristics and reliability of the vertical gallium nitride-based LED device is lowered due to the above problems.

In order to solve the above problems, an object of the present invention further includes a gallium nitride layer which is not doped with an impurity in the n-type gallium nitride layer, and when wet etching to form an uneven pattern on the n-type gallium nitride layer surface The present invention provides a vertical structure gallium nitride-based LED device capable of stably performing a wet etching process without damaging an underlying layer, and a method of manufacturing the same.

 In order to achieve the above object, the present invention comprises the steps of preparing a transparent substrate, forming a first n-type gallium nitride layer on the transparent substrate, the etch stop on the first n-type gallium nitride layer Forming a film, forming a second n-type gallium nitride layer on the etch stop layer, sequentially forming an active layer and a p-type gallium nitride layer on the second n-type gallium nitride layer, and forming a p-type electrode on the p-type gallium nitride layer, forming a structure support layer on the p-type electrode, removing the transparent substrate to expose the first n-type gallium nitride layer, Wet etching the exposed surface of the first n-type gallium nitride layer to form an uneven pattern, and dry-etching the first n-type gallium nitride layer and the etch stop layer on which the uneven pattern is formed to form the second n-type gallium nitride layer. Exposing a portion and the exposed second n It provides a method for producing the vertical structure GaN-based LED element comprises the step of forming an n-type electrode on the gallium nitride layer.

Another object of the present invention is to form an n-type electrode, a first n-type gallium nitride layer formed on the lower surface of the n-type electrode, the surface portion contacting the n-type electrode having an uneven pattern, and the An etch stop layer formed on the bottom surface of the first n-type gallium nitride layer, a second n-type gallium nitride layer formed on the bottom surface of the etch stop layer, an active layer formed on the bottom surface of the second n-type gallium nitride layer, and a bottom surface of the active layer It provides a vertical gallium nitride-based LED device comprising a p-type gallium nitride layer, a p-type electrode formed on the lower surface of the p-type gallium nitride layer and a structure support layer formed on the lower surface of the p-type electrode.

Further, in the vertically structured gallium nitride based LED device of the present invention and a method of manufacturing the same, the etch stop layer is preferably formed of a gallium nitride layer doped with impurities in a thickness range of 100nm to 1000nm.

Further, in the vertically structured gallium nitride based LED device of the present invention and a method of manufacturing the same, the step of wet etching the surface of the n-type gallium nitride layer, the chemical wet etching, electrochemical wet etching and photochemical wet etching method It is preferable to proceed with one wet etching method selected from the group consisting of, or to combine two or more wet etching methods.

In addition, in the vertically structured gallium nitride-based LED device of the present invention and its manufacturing method, the wet etching method, it is preferable to use a KOH solution or H ₃ PO ₄ solution as an etching solution.

In addition, in the vertical structure gallium nitride-based LED device of the present invention and a method of manufacturing the same, before the step of forming a structure supporting layer on the p-type electrode, further comprising the step of forming an adhesive layer on the p-type electrode desirable.

Further, in the vertically structured gallium nitride-based LED device of the present invention and a method of manufacturing the same, the substrate, using any one material selected from the group consisting of sapphire, zinc oxide, gallium nitride, silicon carbide and aluminum nitride It is preferable to form.

Further, in the vertically structured gallium nitride-based LED device of the present invention and a method for manufacturing the same, the n-type gallium nitride layer, the active layer and the p-type gallium nitride layer, Al x In y Ga (1-xy) N composition formula (where 0≤x≤ 1, 0 ≦ y ≦ 1, 0 ≦ x + y ≦ 1).

In addition, in the vertical structure gallium nitride-based LED device of the present invention and a method of manufacturing the same, the structure supporting layer is formed by forming a plating crystal nucleus layer on the p-type electrode, and then using it as a crystal nucleus, or silicon (Si) It is preferable to form using a substrate, a GaAs substrate, a Ge substrate or a metal layer.

The present invention further includes a film having a lower etch rate than the n-type gallium nitride layer in the n-type gallium nitride layer, and by using this as a etch stop layer during wet etching for forming an uneven pattern on the n-type gallium nitride layer surface The wet etching process can be stably performed without damaging the active layer located below the type gallium nitride layer.

In addition, through other etching rates of the etch stop layer, a trench defining an n-type electrode formation region in the n-type gallium nitride layer may be easily formed through a dry etching process without an additional etching amount analysis.

Therefore, the present invention can improve the light extraction efficiency of the vertical gallium nitride-based LED device as well as improve the overall manufacturing yield of the LED device.

Details of the technical structure of the vertical structure gallium nitride-based LED device and its manufacturing method of the present invention will be clearly understood by the following detailed description with reference to the drawings showing preferred embodiments of the present invention.

In the drawings, the thickness of layers, films, panels, regions, etc., are exaggerated for clarity. Like reference numerals designate like parts throughout the specification.

Example

Hereinafter, a method of manufacturing a vertical gallium nitride based LED device according to an embodiment of the present invention will be described in detail with reference to FIGS. 2A to 2F and FIG. 3.

2A to 2F are cross-sectional views sequentially illustrating a method of manufacturing a vertical gallium nitride based LED device according to an exemplary embodiment of the present invention.

First, as shown in FIG. 2A, a buffer layer (not shown), an n-type gallium nitride layer 121, an active layer 122, and a p-type gallium nitride layer 123 are sequentially formed on the light transmissive substrate 110. A light emitting structure 120 having a stacked structure is formed.

In particular, the n-type gallium nitride layer 121 according to the present invention is divided into a first n-type gallium nitride layer 121a and a second n-type gallium nitride layer 121b, and the first n-type gallium nitride layer An etch stop layer 200 is formed at the interface between the second n-type gallium nitride layer and the second n-type gallium nitride layer.

The substrate 110 is a substrate suitable for growing a nitride semiconductor single crystal, and is preferably formed using a transparent material including sapphire. In addition to sapphire, the substrate 110 may be formed of zinc oxide (ZnO), gallium nitride (GaN), silicon carbide (SiC), aluminum nitride (AlN), or the like.

The buffer layer (not shown) is a layer for improving lattice matching with the substrate 110 including the sapphire before growing the first n-type gallium nitride layer 121a on the substrate 110. In general, AlN / GaN is formed and may be omitted depending on the characteristics of the device and process conditions.

The n-type gallium nitride layer 121, the active layer 122, and the p-type gallium nitride layer 123, Al x In y Ga (1-xy) N composition formula (where 0≤x≤1, 0≤y≤1, 0≤ x + y ≦ 1), and may be formed by an epitaxial growth method using a metal organic chemical vapor deposition (MOCVD) facility. More specifically, the n-type gallium nitride layer 121 may be formed of a GaN layer or a GaN / AlGaN layer doped with n-type conductive impurities, for example, Si, Ge , Sn and the like are used, and preferably Si is mainly used. In addition, the p-type gallium nitride layer 123 may be formed of a GaN layer or a GaN / AlGaN layer doped with a p-type conductive impurity, for example, Mg, Zn, Be Etc., and Mg is mainly used preferably. In addition, the active layer 122 may be formed of an InGaN / GaN layer having a multi-quantum well structure.

On the other hand, the active layer 122 may be formed of one quantum well layer or a double hetero structure. In addition, the active layer 122 determines whether the diode is a green light emitting device or a blue light emitting device by the amount of indium (In) constituting it. More specifically, about 22% of indium is used for light emitting devices having blue light, and about 40% of indium is used for light emitting devices having green light. That is, the amount of indium used to form the active layer 122 varies depending on the required blue or green wavelength.

Therefore, the active layer 122 has a great influence on the characteristics and reliability of the gallium nitride-based LED device as described above, and thus, cracks or conductive materials penetrate the overall gallium nitride-based LED device manufacturing process. It should be safe from the same defect.

The present invention provides a first n of the n-type gallium nitride layer 121 to prevent the active layer 122 from being damaged by a wet etching process of forming an uneven pattern on the n-type gallium nitride layer 121. An etch stop layer 200 is further formed at an interface between the type gallium nitride layer 121a and the second n-type gallium nitride layer 121b.

Accordingly, the etch stop layer 200 may be formed of a material having a lower etch rate than the second n-type gallium nitride layer 121b and the first n-type gallium nitride layer 121a in contact with the active layer 122. In this embodiment, a gallium nitride layer which is not doped with impurities is used as the material.

In addition, the etch stop film 200 is preferably formed in a thickness of 100nm to 1000nm in order to serve as a stop film.

Next, as shown in FIG. 2B, a p-type electrode 130 is formed on the p-type gallium nitride layer 123. In this case, the p-type gallium nitride layer 123, the conductivity is relatively poor compared to the n-type gallium nitride layer 121, and is mainly formed of a thin thickness of 1㎛ or less and very close to the pn junction characteristics Therefore, in consideration of electrical and thermal characteristics, it is preferable to form an ohmic characteristic and a light reflection characteristic on the entire upper surface of the p-type gallium nitride layer 123. In other words, the p-type electrode 130 may be formed as a single layer made of a metal having both ohmic and light reflecting properties or a multilayer formed by sequentially stacking metals having both ohmic and light reflecting properties.

Subsequently, the structural support layer 150 formed of a plating layer formed by electroplating or electroless plating using the plating crystal nucleus layer 140 is formed on the p-type electrode 130.

Meanwhile, in the present embodiment, the plating layer formed by using the plating crystal nucleus layer 140 as the crystal nucleus as the structure support layer 150 is described, but the present invention is not limited thereto, and the structure supporting layer may be a supporting layer and an electrode of the final LED device. As a role to play, it can be formed using a silicon (Si) substrate, a GaAs substrate, a Ge substrate or a metal layer.

Next, as shown in FIG. 2C, the substrate 110 is removed through an LLO process.

Subsequently, as shown in FIG. 2D, a portion of the surface of the first n-type gallium nitride layer 121a of the n-type gallium nitride layer 121 separated and exposed from the substrate (not shown) is wet-etched to form an uneven pattern. To form 160.

The wet etching for forming the concave-convex pattern 160 on the surface of the first n-type gallium nitride layer 121a may include one selected from the group consisting of chemical wet etching, electrochemical wet etching, and photochemical wet etching. The wet etching may be performed or a combination of two or more wet etching methods may be used.

In addition, as the wet etching solution, a KOH solution, a H ₃ PO ₄ solution, or the like is used.

Accordingly, the present invention is located below the first n-type gallium nitride layer 121a, and the second n-type gallium nitride layer 121b as the lower layer during wet etching by the etch stop layer 200 having a lower etch rate than the first n-type gallium nitride layer 121a. It is possible to form the uneven pattern 160 safely without damaging.

In FIG. 2D, the entire thickness of the first n-type gallium nitride layer 121a is etched to form an uneven pattern 160 on the etch stop layer 200, but the present invention is not limited thereto. As shown in FIG. 3, the uneven pattern 160 may be formed only on a portion of the upper surface of the first n-type gallium nitride layer 121a according to the characteristics of the device and the process conditions. 3 is a cross-sectional view illustrating a modified example of a manufacturing method of a vertical gallium nitride based LED device according to an exemplary embodiment of the present invention.

Next, as shown in FIG. 2E, the first n-type gallium nitride layer 121 on which the uneven pattern 160 is formed and a portion of the etch stop layer 200 positioned thereunder are selectively dry-etched to form n-type. The trench 170 defining the electrode formation region is formed.

On the other hand, conventionally there was a problem in the process, such as having to check the signal indicating the change in the etching amount through the controller to perform a separate end point detector (EPD) function in order to control the depth of the trench 170, According to the present invention, the n-type gallium nitride layer 121 and the etch stop layer 200 may be etched to a desired point without further analysis through different etching rates.

That is, the etch stop layer 200 according to the present invention compares the etch rate with the n-type gallium nitride layer 121, and both the wet etch rate and the dry etch rate are greater than those of the n-type gallium nitride layer 121. When the etching process of forming the trench 170 is performed, the amount of etching that is etched within the unit time during the etching stop layer 200 under the n-type gallium nitride layer 121 is significantly reduced. Able to know.

Next, as illustrated in FIG. 2F, a conductive material having ohmic characteristics is deposited on the trench 170 formed in the n-type gallium nitride layer 121 to form an n-type electrode 180.

Although the preferred embodiments of the present invention have been described in detail above, those skilled in the art will understand that various modifications and equivalent other embodiments are possible therefrom. Accordingly, the scope of the present invention is not limited thereto, and various modifications and improvements of those skilled in the art using the basic concept of the present invention as defined in the following claims also fall within the scope of the present invention.

1A to 1F are cross-sectional views sequentially illustrating a method of manufacturing a vertical gallium nitride based LED device according to the prior art.

2A to 2F are cross-sectional views sequentially illustrating a method of manufacturing a vertical gallium nitride based LED device according to an exemplary embodiment of the present invention.

Figure 3 is a cross-sectional view showing a modification of the manufacturing method of the vertical structure gallium nitride-based LED device according to an embodiment of the present invention.

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

110 substrate 120 light emitting structure

121: n-type gallium nitride layer 122: active layer

123: p-type gallium nitride layer 130: p-type electrode

150: structural support layer 160: uneven pattern

170: trench 180: n-type electrode

200: etching stop film

Claims (19)

Preparing a substrate; Forming a first n-type gallium nitride layer on the substrate; Forming an etch stop layer on the first n-type gallium nitride layer; Forming a second n-type gallium nitride layer on the etch stop layer; Sequentially forming an active layer and a p-type gallium nitride layer on the second n-type gallium nitride layer; Forming a p-type electrode on the p-type gallium nitride layer; Forming a structure support layer on the p-type electrode; Removing the substrate to expose the first n-type gallium nitride layer; Wet etching the surface of the exposed first n-type gallium nitride layer to form an uneven pattern; Dry etching the first n-type gallium nitride layer and the etch stop layer on which the uneven pattern is formed to expose a portion of the second n-type gallium nitride layer; And Forming an n-type electrode on the exposed second n-type gallium nitride layer; Method of manufacturing a vertical gallium nitride-based LED device comprising a. The method of claim 1, The etch stop layer is a method of manufacturing a vertical gallium nitride-based LED device, characterized in that formed using a gallium nitride layer doped with impurities. The method of claim 1, The etch stop layer is a manufacturing method of a vertical gallium nitride-based LED device, characterized in that formed in a thickness of 100nm to 1000nm range. The method of claim 1, The wet etching of the surface of the first n-type gallium nitride layer may be performed by one wet etching method selected from the group consisting of a chemical wet etching method, an electrochemical wet etching method, and a photochemical wet etching method, or two or more wet etching methods. Method of manufacturing a vertical gallium nitride-based LED device, characterized in that to proceed in combination. The method of claim 4, wherein The wet etching method is a method of manufacturing a vertical gallium nitride-based LED device, characterized in that using the KOH solution or H ₃ PO ₄ solution as an etching solution. The method of claim 1, Before forming the structure support layer on the p-type electrode, The method of manufacturing a vertical gallium nitride-based LED device, characterized in that further comprising the step of forming an adhesive layer on the p-type electrode. The method of claim 1, The substrate is a method of manufacturing a vertical gallium nitride-based LED device, characterized in that formed using any one material selected from the group consisting of sapphire, zinc oxide, gallium nitride, silicon carbide and aluminum nitride. The method of claim 1, The n-type gallium nitride layer, the active layer, and the p-type gallium nitride layer have an Al x In y Ga (1-xy) N composition formula, where 0 ≦ x ≦ 1, 0 ≦ y ≦ 1, and 0 ≦ x + y ≦ 1. A method of manufacturing a vertical gallium nitride based LED device, characterized in that formed of a semiconductor material. The method of claim 1, The structure supporting layer is a method of manufacturing a vertical gallium nitride-based LED device, characterized in that to form a plated crystal nucleus layer on the p-type electrode, and then using it as a crystal nucleus. The method of claim 1, The structure supporting layer is a silicon (Si) substrate, a GaAs substrate, a Ge substrate or a metal layer manufacturing method of manufacturing a vertical gallium nitride-based LED device, characterized in that formed using a metal layer. n-type electrode; A first n-type gallium nitride layer formed on a lower surface of the n-type electrode and having a portion of a surface in contact with the n-type electrode having an uneven pattern; An etch stop layer formed on the bottom surface of the first n-type gallium nitride layer; A second n-type gallium nitride layer formed on the lower surface of the etch stop layer; An active layer formed on a lower surface of the second n-type gallium nitride layer; A p-type gallium nitride layer formed on the lower surface of the active layer; A p-type electrode formed on the lower surface of the p-type gallium nitride layer; And And a structure supporting layer formed on the bottom surface of the p-type electrode. The method of claim 11, The etch stop layer is a vertical structure gallium nitride-based LED device, characterized in that consisting of a gallium nitride layer doped with impurities. The method of claim 11, The etch stop layer is a vertical structure gallium nitride-based LED device, characterized in that formed in a thickness of 100nm to 1000nm range. The method of claim 11, The uneven pattern formed on the surface of the first n-type gallium nitride layer may be formed using one wet etching method selected from the group consisting of chemical wet etching, electrochemical wet etching, and photochemical wet etching, or two or more wet etching methods. Vertical structure gallium nitride-based LED device, characterized in that formed using a combination. The method of claim 14, The wet etching method is a vertical gallium nitride-based LED device, characterized in that using the KOH solution or H ₃ PO ₄ solution as an etching solution. The method of claim 11, The vertical structure gallium nitride-based LED device further comprises an adhesive layer formed at the interface between the p-type electrode and the structure support layer. The method of claim 11, The substrate is a vertical gallium nitride-based LED device, characterized in that made of any one material selected from the group consisting of sapphire, zinc oxide, gallium nitride, silicon carbide and aluminum nitride. The method of claim 11, The n-type gallium nitride layer, the active layer, and the p-type gallium nitride layer have an Al x In y Ga (1-xy) N composition formula, where 0 ≦ x ≦ 1, 0 ≦ y ≦ 1, and 0 ≦ x + y ≦ 1. Vertical structure gallium nitride-based LED device, characterized in that made of a semiconductor material. The method of claim 11, The structure support layer is a vertical structure gallium nitride-based LED device, characterized in that made of any one selected from the group consisting of a plating layer, a silicon (Si) substrate, a GaAs substrate, a Ge substrate or a metal layer.

Images