KR100593543B1 - Nitride semiconductor light emitting device and its manufacturing method - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a nitride semiconductor light emitting device and a method for manufacturing the same, wherein a metal group in which at least one metal oxide-producing metal and a current diffusion metal are respectively mixed is deposited on a p-nitride semiconductor layer. By forming the electrode, metal oxides are more easily formed during the deposition of the transparent electrode, and excessive generation of metal oxides can be suppressed to facilitate current diffusion into the light emitting layer, thereby lowering the driving voltage of the device. It is possible to increase the life of the light emitting device.

     Nitride, luminescence, transparent, electrode, metal, oxide

Description

Nitride semiconductor light emitting device and method for manufacturing the same

1 to 2 illustrate a conventional nitride semiconductor light emitting device as an example;

3A to 3D illustrate a method of manufacturing a semiconductor light emitting device according to the first embodiment of the present invention;

4A to 4C illustrate a method of manufacturing a semiconductor light emitting device according to a second embodiment of the present invention;

5A to 5B are graphs of oxide topologies and experimental results of light emitting devices formed according to a conventional manufacturing method;

6A to 6B are graphs of oxide topologies and experimental results of light emitting devices formed according to the manufacturing method of the present invention.

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

        10, 20: substrate 11, 21: n-nitride semiconductor layer

        12, 22: light emitting layer 13, 23: p-nitride semiconductor layer

        14, 24, 30: transparent electrode 15, 25: electrode for p pad

 16, 26: n pad electrode

The present invention relates to a semiconductor light emitting device and a method for manufacturing the same, which can facilitate diffusion of current to the light emitting layer by suppressing excessive generation of metal oxide during transparent electrode deposition.

In general, nitride semiconductors are directly transition type and have high luminous efficiency and have been used to form emission wavelengths from red to violet and ultraviolet region. In particular, as the understanding of the growth method and structure is advanced, the characteristics of the light emitting device, That is, significant improvements have been made in brightness, driving voltage, or electrostatic characteristics.

However, despite these efforts, there is still a high demand for high output and low driving voltage, and research on nitride semiconductor light emitting devices that output long wavelengths (yellow and red light) and short wavelengths (ultraviolet) is still needed. 1 is a view showing the structure of a conventional nitride semiconductor light emitting device.

As shown in the drawing, the conventional nitride semiconductor light emitting device is abbreviated as GaN layer 11 (hereinafter, referred to as symbol "-") which is doped with n-type dose on the sapphire substrate 10. ), The light emitting layer 12 and the p-GaN layer 13 are sequentially formed, and are vertically mesa-etched from the p-GaN layer 13 to a part of the n-GaN layer 11. The n pad electrode 16 is formed on the n-GaN layer 11, and the transparent electrode 14 and the p pad electrode 15 are sequentially formed on the p-GaN layer 13.

On the other hand, Figure 2 is a view showing a structure of another conventional nitride semiconductor light emitting device, that is, a semiconductor light emitting device of the top-down electrode type, as shown therein, n on the silicon carbide (SiC) substrate 20 A GaN layer 21, a light emitting layer 22, a p-GaN layer 23, and a transparent electrode 24 are sequentially formed. An n-pad electrode 26 is formed below the silicon carbide substrate 20. The p-pad electrode 25 is formed on the transparent electrode 24.

In the conventional nitride semiconductor light emitting devices having such a structure, in particular, the transparent electrode facilitates current diffusion to lower the driving voltage of the device and improves quantum efficiency by allowing light generated in the light emitting layer to be emitted to the outside. To this end, for this purpose, a metal layer for forming metal oxides such as Ni, Pd, Pt, and the like, and a current diffusion metal such as Au, are formed in two or more layers, and Ni and Au are mainly used.

For example, a first metal layer is deposited on the p-GaN layer by using metal oxide generation metal Ni, and then a second metal layer is deposited on the first metal layer by using current diffusion metal Au to form a transparent electrode.

At this time, as Ni is oxidized, a metal oxide such as NiO is formed, which serves to supply holes to the p-GaN layer.

However, since these metal oxides are mostly poor in electrical conductivity, they prevent the current supplied from the outside from diffusing into the light emitting layer, thus preventing excessive formation, except for supplying a predetermined amount of holes. There is a need.

However, the above-described conventional method, that is, a method of forming a transparent electrode by depositing two or more metal layers in p-GaN by an individual deposition process, is oxidized from the contact surface between the p-GaN layer and the lowest metal layer of the transparent electrode and the transparent electrode. There is a problem that a large amount of metal oxide is produced as a whole up to the top metal layer.

Therefore, it is necessary to prevent the metal oxide from being excessively formed during the formation of the transparent electrode, and to minimize the suppression of current diffusion into the light emitting layer due to the metal oxide.

Accordingly, the present invention was developed to satisfy the above necessity, and provides a nitride semiconductor light emitting device and a method of manufacturing the same, which facilitate the diffusion of current into the light emitting layer by suppressing excessive generation of metal oxide during the deposition of a transparent electrode. Its purpose is to.

In accordance with this purpose, the present invention is to mix the metal oxide generation metal and the current diffusion metal in advance to deposit two or more kinds of the mixed metal on the p-nitride semiconductor layer, in addition, nitrogen and oxygen during deposition It is preferable to apply heat within a predetermined range to form an ohmic contact in a mixed atmosphere.

To this end, the present invention according to the first embodiment, a first step of sequentially forming an n-doped nitride semiconductor layer, a light emitting layer, a p-doped nitride semiconductor layer on the substrate;

A second step of exposing a portion of the n-doped nitride semiconductor layer by mesa etching in a vertical direction from a p-doped nitride semiconductor layer formed in the first step to a portion of the n-doped nitride semiconductor layer;

On the upper portion of the p-doped nitride semiconductor layer which is not etched in the second step, a metal group in which at least one metal oxide metal and current diffusion metal are mixed is deposited. Forming a third step;

A nitride semiconductor light emitting device is fabricated through a fourth step of forming a pad electrode on an upper portion of the n-doped nitride semiconductor layer exposed in the second step and an upper portion of the transparent electrode formed in the fourth step.

The present invention according to the second embodiment includes a first step of sequentially forming an n-doped nitride semiconductor layer, an emission layer, and a p-doped nitride semiconductor layer on the substrate;

On the p-doped nitride semiconductor layer formed in the first step, a metal group in which at least one or more kinds of a metal oxide generation metal and a current diffusion metal is mixed to form a transparent electrode to form a transparent electrode Two steps;

Through the third step of forming a pad electrode on each of the upper portion of the transparent electrode formed in the second step and the lower portion of the substrate of the first step, a nitride semiconductor light emitting device is manufactured.

Hereinafter, the present invention will be described with reference to the accompanying drawings.

First, a first embodiment of the method for manufacturing a nitride semiconductor light emitting device according to the present invention will be described with reference to FIGS. 3A to 3D. The definition of “transparent” of the present invention indicates when light is transmitted by 10% or more. This does not mean no color or transparency.

<First Embodiment>

First, according to the first embodiment of the present invention, as shown in FIG. 3A, the n-nitride semiconductor layer 11, the light emitting layer 12, and the p-nitride semiconductor layer 13 are sequentially formed on the substrate 10. To form.

That is, a nitride semiconductor is deposited on the substrate, grown to a predetermined thickness by using a metal organic vapor phase epitaxy (MOVPE) growth method, and then doped with an n-type dose to n-nitride semiconductor layer 11. The light emitting material and the nitride semiconductor are sequentially deposited on the n-nitride semiconductor layer, and the nitride semiconductor is grown to a predetermined thickness and doped with a p-type dose to form a p-nitride semiconductor layer. do.

The substrate 10 is a heterogeneous substrate, and a sapphire substrate is used, and the n-nitride semiconductor layer 11 is grown to a thickness of about 1 μm to 500 μm, and then Si, Ge, Se, S, It is preferably formed by doping with any one n-type dose selected from Te and the like. In addition, the p-nitride semiconductor layer 13 is a nitride semiconductor layer doped with any one of p-type dose selected from Be, Sr, Ba, Zn, Mg, etc., for example, p-GaN layer, p-AlGaN As a layer and a p-InGaN layer, it is preferable to make the thickness into about 0.1 micrometer-about 100 micrometers.

Next, when the n-nitride semiconductor layer 11, the light emitting layer 12, and the p-nitride semiconductor layer 13 are sequentially formed on the substrate 10, the p-nitride semiconductor layer 13 to the n-nitride semiconductor layer are formed. A portion of the n-nitride semiconductor layer 11 is exposed by etching mesa in a vertical direction to a portion of (11) (FIG. 3B).

Thereafter, the predetermined metal group prepared in advance for the present invention, that is, the predetermined metal group in which at least one or more of each of the metal oxide generation metal and the current diffusion increasing metal are mixed, is etched. It is deposited on the remaining p-nitride semiconductor layer 13 to form a transparent electrode 30 (FIG. 3C).

That is, on the upper part of the p-nitride semiconductor layer 13, a metal for producing metal oxide, for example, any one metal selected from Ni, Pd, Pt, Pu, Ir, Zn, and Mg, and for increasing current diffusion such as Au A metal group in which at least one metal is mixed is deposited to form a transparent electrode 30. It is most preferable to form a transparent electrode by depositing a metal group in which Ni and Au are mixed as much as possible.

As described above, when a predetermined metal group in which at least one of the metal oxide generation metal and the current diffusion increasing metal are respectively mixed is deposited on the p-nitride semiconductor layer to form a transparent electrode, When the metal group is deposited, the contact surface of the p-nitride semiconductor layer and the transparent electrode is oxidized to generate a metal oxide that supplies holes to the p-nitride semiconductor layer, for example, to the p-GaN layer. Due to the more active oxidation reactions on the metal group and the metal group surface, relatively less metal oxides are formed in the vicinity of the contact surface than in the prior art.

That is, according to the present invention, when a predetermined metal group is deposited on the p-nitride semiconductor layer to form a transparent electrode, a metal for producing metal oxide, for example, Ni, which forms the metal group, starts from the surface of the p-nitride semiconductor layer. Since it is evenly distributed up to the top of the transparent electrode, it is much easier to form a metal oxide than conventionally.

In addition, since less metal oxide is formed in the vicinity of the contact surface with the p-nitride semiconductor layer than in the related art, the ohmic contact resistance value is relatively lower than in the related art, thereby making ohmic contact easily.

In addition, in the present invention, when the above-described predetermined metal group is deposited on the p-nitride semiconductor layer for forming the transparent electrode, nitrogen (N ₂ ) is slightly oxygen (O ₂ ) in addition to this. It is desirable to apply heat within a temperature range of approximately 400 ° C. to 1000 ° C. in a mixed atmosphere to make ohmic contact formation much easier.

Meanwhile, according to the present invention, when a predetermined metal group is deposited on the p-nitride semiconductor layer 13 to form the transparent electrode 30, finally, the upper portion of the transparent electrode 30 thus formed and n A pad electrode which is formed by depositing a metal in which any one or two or more selected from Cr, Al, Ni, Au, Pt, Ti, and the like is mixed on the exposed portion of the nitride semiconductor layer 11 and electrically connected to the outside ( 15, 16) to terminate the first embodiment of the present invention.

Next, a second embodiment of the present invention will be described with reference to FIGS. 4A to 4C. The second embodiment of the present invention is applied to a method for manufacturing a top-down electrode type semiconductor light emitting device.

Second Embodiment

First, according to the second embodiment of the present invention, as shown in FIG. 4A, the n-nitride semiconductor layer 21, the light emitting layer 22, and the p-nitride semiconductor layer 23 are sequentially formed on the substrate 20. The forming process is the same as in the above-described first embodiment, and thus description thereof will be omitted.

Subsequently, on top of the p-nitride semiconductor layer 23, a predetermined group of metals, each of which a metal oxide generation metal and a current diffusion increasing metal, are mixed at least one or more of them, is deposited. 30) (FIG. 4B).

That is, on the upper part of the p-nitride semiconductor layer 23, a metal for generating metal oxide, for example, any one metal selected from Ni, Pd, Pt, Pu, Ir, Zn, and Mg, and for increasing current diffusion such as Au At least one metal group is deposited to form a transparent electrode 30 by depositing a metal group mixed with at least one metal. A metal group mixed with Ni and Au is deposited to form a transparent electrode. It is most preferable to form a transparent electrode by applying heat at a temperature in the range of 300 ° C to 1000 ° C in an atmosphere such as (N ₂ ) or oxygen (O ₂ ).

Finally, a metal in which any one or two or more selected from among Ni, Au, Pt, Ti, and the like is mixed is deposited on the upper portion of the transparent electrode 30 thus formed and the lower portion of the substrate 20. The second embodiment of the present invention is terminated by patterning a stripe, thereby forming pad electrodes 25 and 26 electrically connected to the outside (FIG. 4C).

Next, the characteristic results of the semiconductor light emitting device manufactured according to the present invention will be described with reference to FIGS. 5A to 5B and FIGS. 6A to 6B.

5A to 5B are graphs of measurement through an oxide topology and an experimental example 1 of a light emitting device formed according to a conventional manufacturing method.

Experimental Example 1

1. In this experimental example, a sapphire substrate was used as a substrate, gallium nitride (GaN), a group III-V compound, as a nitride semiconductor, and Ni and Au were sequentially deposited on a p-doped gallium nitride layer. The thickness of the transparent electrode was about 1 nm to 100 nm.

2. The heat treatment temperature during the formation of the transparent electrode was about 600 ℃, the tolerance range of the heat treatment temperature to obtain the same results as the measurement results of the present experimental example is about 600 ℃ to ± 100 ℃.

3. At the time of heat treatment, the atmosphere was mixed with some oxygen in nitrogen, and RTA (Rapid Thermal Annealing) equipment was used as the heat treatment equipment.

6A to 6B are graphs of measurement through an oxide topology of the light emitting device formed according to the manufacturing method of the present invention and Experimental Example 2 below.

Experimental Example 2

This Experimental Example 2 was formed by depositing a predetermined metal group in which Ni and Au are mixed in the transparent electrode according to the present invention, and the rest of the experimental conditions are the same as in Experimental Example 1 described above.

As measured by Experimental Example 1 and Experimental Example 2, as shown in Figures 5a and 6a, as the sputtering time has elapsed, according to the conventional method than the semiconductor light emitting device manufactured according to the present invention It can be seen that the manufactured semiconductor light emitting device has a relatively larger amount of NiO, which is a metal oxide, which is unnecessary at a predetermined amount or more. As a result, the lifespan of the device is reduced. As can be seen from the above experiment, the present invention can reduce NiO, which is a metal oxide, to lower the driving voltage of the device. The lifetime of the device can also be increased.

As described above in detail, the nitride semiconductor light emitting device and the method of manufacturing the same according to the present invention can easily form a metal oxide during the deposition of a transparent electrode, and suppress the excessive generation of the metal oxide to the light emitting layer. By allowing the current to be easily spread, the driving voltage of the device can be lowered to increase the life of the light emitting device.

Although the invention has been described in detail only with respect to the specific examples described, it will be apparent to those skilled in the art that various modifications and variations are possible within the spirit of the invention, and such modifications and variations belong to the appended claims.

Claims (9)

Sequentially forming an n-doped nitride semiconductor layer, an emission layer, and a p-doped nitride semiconductor layer on the substrate; Mesa etching a vertical direction from the p-doped nitride semiconductor layer to a portion of the n-doped nitride semiconductor layer to expose a portion of the n-doped nitride semiconductor layer; Forming a transparent electrode on the p-doped nitride semiconductor layer remaining unetched by depositing a metal group in which at least one metal oxide generation metal and at least one current diffusion metal are mixed; ; And forming a pad electrode on each of the exposed n-doped nitride semiconductor layer and an upper portion of the formed transparent electrode. Sequentially forming an n-doped nitride semiconductor layer, an emission layer, and a p-doped nitride semiconductor layer on the substrate; Forming a transparent electrode on the p-doped nitride semiconductor layer by depositing a metal group in which at least one metal oxide generation metal and current diffusion metal are respectively mixed; Forming a pad electrode on an upper portion of the transparent electrode and a lower portion of the substrate. The method of claim 1 or 2, wherein the substrate; A sapphire substrate or a silicon carbide substrate, characterized in that the nitride semiconductor light emitting device manufacturing method. The method of claim 1 or 2, wherein the metal oxide generating metal; Ni, Pd, Pt, Ir, Zn, Mg any one selected from the group consisting of, or a mixture of two or more, characterized in that the nitride semiconductor light emitting device manufacturing method. The method of claim 1 or 2, wherein the current spreading metal; It is Au, The nitride semiconductor light emitting element manufacturing method characterized by the above-mentioned. The method of claim 1, wherein the forming of the transparent electrode comprises: On the p-doped nitride semiconductor layer, a metal group in which at least one metal oxide generation metal and at least one metal for current diffusion are mixed is deposited, and at the same time, nitrogen (N ₂ ) or oxygen (O) is deposited. ₂ ) or a heat treatment in an atmosphere in which nitrogen (N ₂ ) and oxygen (O ₂ ) are mixed to form a transparent electrode. Sequentially forming an n-doped nitride semiconductor layer, a light emitting layer, and a p-doped nitride semiconductor layer on the substrate; Forming an n-pad electrode on an n-doped nitride semiconductor layer exposed by mesa etching in a vertical direction from the p-doped nitride semiconductor layer to a portion of the n-doped nitride semiconductor layer; Depositing a metal group on which the metal oxide generation metal and the current diffusion metal are respectively mixed, on the p-doped nitride semiconductor layer remaining unetched to form a transparent electrode; A nitride semiconductor light emitting device manufactured by forming a p-pad electrode on the transparent electrode. Sequentially forming an n-doped nitride semiconductor layer, a light emitting layer, and a p-doped nitride semiconductor layer on the substrate; Depositing a metal group on which the metal oxide generation metal and the current diffusion metal are respectively mixed on the p-doped nitride semiconductor layer to form a transparent electrode; A nitride semiconductor light emitting device manufactured by forming a pad electrode on each of an upper portion of the transparent electrode and a lower portion of the substrate. delete

Images