KR101188915B1 - Group 3 n-type nitride-based semiconductors having improved thermal stability, and method of manufacturing the same - Google Patents

Abstract

In the present invention, a group III n-nitride semiconductor device is disclosed, comprising a structure in which a nitride layer is formed on an n-type nitride cladding layer of the semiconductor device. In the group III n-type nitride semiconductor device and the light emitting diode device including the same, the nitride layer is formed while the nitrogen of the n-type nitride cladding layer is released by laser irradiation, and the n-type nitride cladding The formation of N vacancies in the layer facilitates current movement due to tunneling due to an increase in carrier concentration on the surface of the n-type nitride cladding layer, as well as ensuring thermal stability and maintaining ohmic characteristics. Have Therefore, according to the present invention, there is an advantage that a group III n-type nitride semiconductor device having improved electrical or thermal stability and a light emitting diode device including the same can be used.

Description

Group III n-type nitride-based semiconductor device having improved thermal stability and method of manufacturing the same {Group III n-type nitride-based semiconductors having improved thermal stability, and method of manufacturing the same}

The present invention relates to a Group III n-type nitride semiconductor device, and more particularly, to a Group III n-type nitride semiconductor device having improved thermal stability, a method of manufacturing the same, and a light emitting diode device including the same.

A light emitting diode (LED) is a semiconductor device capable of generating light of various colors based on recombination of electrons and holes at a junction portion of a p and n type semiconductor when current is applied thereto. These LEDs have a number of advantages, such as long life, low power, excellent initial driving characteristics, high vibration resistance, and high tolerance for repetitive power interruptions, compared to filament based light emitting devices. In particular, in recent years, group III nitride semiconductor devices capable of emitting light in a blue short wavelength region have been in the spotlight.

On the other hand, the ohmic characteristic refers to a case in which the I-V curve follows the general Ohm's law when the current according to the voltage is measured. In particular, in the contact between the semiconductor and the metal, the n-type semiconductor exhibits an ohmic characteristic when the work function of the n-type semiconductor is larger than that of the metal, and the p-type exhibits an ohmic characteristic on the contrary. .

The nitride single crystal constituting the light emitting diode using the group III nitride semiconductor device as described above is formed on a single crystal growth substrate such as sapphire or SiC substrate. The nitride-based light emitting diodes are divided into two types depending on the shape of the light emitting device and the manner in which light generated in the nitride-based active layer is emitted to the outside. First, classification according to the shape of the light emitting device is performed by the electrical characteristics of the supporting substrate. The nitride-based light emitting structure is grown on the upper layer of the insulating growth substrate like the sapphire material, and the n-type and p-type ohmic electrode layers are in the same direction. Mesa structured nitride-based LEDs arranged horizontally and vertical structures grown on upper layers of conductive growth substrates, such as silicon (Si) and silicon carbide (SiC), unlike insulated sapphire growth substrates Is a nitride structured nitride-based LED. In terms of light brightness, heat removal, and device reliability, there are many advantages of vertical structured nitride-based LEDs fabricated on top of conductive substrates that are electrically and thermally superior to mesa-based nitride LEDs. It has In addition, depending on whether light generated in the active layer of the nitride-based light emitting device is emitted to the outside through the p-type ohmic electrode layer or the substrate (top) emitting light emitting diode (top-emitting light emitting diode) and flip It is divided into a flip-chip light emitting diode. Nitride-based top-emitting light emitting diodes emit light generated from the nitride-based active layer to the outside through the p-type ohmic electrode layer, whereas nitride-based flip chip type light emitting diodes use a highly reflective p-type ohmic electrode layer to form a nitride-based light emitting structure. The light generated in is emitted to the outside through the transparent substrate (sapphire).

Meanwhile, Group III nitride semiconductor devices such as GaN have been spotlighted as core materials of light emitting devices such as light emitting diodes (LEDs) or laser diodes (LDs) due to their excellent physical and chemical properties. LEDs or LDs using a III-nitride-based semiconductor device material are widely used in light emitting diodes for obtaining light in a blue or green wavelength band, and such light emitting diodes are used as light sources of various products such as electronic displays and lighting devices. The group III nitride semiconductor device is generally made of a GaN material having a composition formula of In x Al y Ga (1-xy) N (0≤x≤1, 0≤y≤1, 0≤x + y≤1). have. In general, a light emitting diode using a group III nitride semiconductor device includes an n-type GaN-based cladding layer, a single quantum well structure, or a multi-quantum well-structured active layer and a p-type GaN-based cladding layer on a sapphire substrate that is an insulating substrate. It has a basic structure stacked sequentially.

However, when the sapphire substrate is separated from the structure and the structure is reversed, the n-type GaN-based cladding layer on the nitrogen polar surface is exposed to the air, and the nitride is sequentially disposed on the lower surface of the n-type GaN-based cladding layer on the nitrogen polar surface. It has a structure in which an active layer and a p-type GaN cladding layer are laminated. In this case, the n-type GaN-based cladding layer having a nitrogen polar surface has a different surface characteristic from the p-type GaN-based cladding layer having a group III metal polar surface, and the Ti / Al layer is used as an ohmic contact layer in the n-type GaN layer. To form a device.

On the other hand, the group III n-type nitride semiconductor device as described above has a problem that the ohmic characteristics of the Ti / Al ohmic contact layer of the group III n-type nitride semiconductor device during heat treatment is reduced. Therefore, there has been a demand for the development of a layer capable of maintaining ohmic characteristics even during heat treatment and preventing Ga from diffusing into the electrode structure.

Accordingly, the present inventors have made a thorough effort to develop a semiconductor device that can solve the above-mentioned problems in the prior art, and thus, the present invention has been completed.

As a result, the present invention provides a group III n-type nitride semiconductor device and a light emitting diode device including the same, which improve thermal stability by irradiating a laser to the electrode structure in order to maintain the ohmic characteristics during heat treatment. have.

 In the present invention, there is provided a group III n-nitride semiconductor device comprising a structure in which a nitride layer is formed on an n-type nitride cladding layer of the semiconductor device.

According to an embodiment of the present invention, the semiconductor device has a structure having a composition formula of In x Al y Ga (1-xy) N (0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ x + y ≦ 1). It may include.

According to an embodiment of the present invention, the nitride layer may be formed from nitrogen of the n-type nitride cladding layer by laser irradiation.

According to another aspect of the invention, the electrode structure; Nitride layer; n-type nitride cladding layer; Nitride-based active layer; A p-type nitride cladding layer of a metal polar surface; Reflective p-type ohmic contact electrode structures; And a group III n-type nitride-based semiconductor device comprising a structure in which a support substrate is stacked.

According to an embodiment of the present invention, the semiconductor device has a structure having a composition formula of In x Al y Ga (1-xy) N (0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ x + y ≦ 1). It may include.

According to an embodiment of the present invention, the nitride layer may be formed from nitrogen of the n-type nitride cladding layer by laser irradiation.

According to an embodiment of the present invention, the n-type nitride cladding layer and the p-type nitride cladding layer may be n-GaN and p-GaN, respectively.

According to an embodiment of the present invention, the nitride based active layer may have a single quantum well structure or a multiple quantum well structure.

According to another aspect of the invention, the step of sequentially growing an n-type nitride cladding layer of the nitrogen polar surface, a nitride active layer, and a p-type nitride cladding layer of the metal polar surface on the growth substrate; Forming a reflective p-type ohmic contact electrode structure on an upper surface of the p-type nitride cladding layer; Forming a support substrate on an upper surface of the reflective p-type ohmic contact electrode structure; Separating and removing the growth substrate; Forming an electrode structure on an upper surface of the n-type nitride cladding layer; And a group III n-type nitride semiconductor device comprising laser irradiation on the electrode structure.

According to one embodiment of the invention, the laser irradiation may be performed in any one of air, nitrogen, argon, and a vacuum atmosphere.

According to an embodiment of the present invention, the laser irradiation energy may be 300 to 900 mJ / cm ² .

According to an embodiment of the present invention, the electrode structure may further include one or more barrier materials selected from the group consisting of Pt, Ti, Mo, W, and TiN.

According to an embodiment of the present invention, after the separating and removing the growth substrate, the method may further include forming a pattern on the n-type nitride cladding layer.

In the group III n-type nitride semiconductor device and the light emitting diode device including the same, a nitride layer is formed while nitrogen is released from the n-type nitride cladding layer by laser irradiation, and a nitrogen pore is formed in the n-type nitride cladding layer. By forming (N vacancy), not only can current flow smoothly by tunneling due to an increase in carrier concentration on the surface of the n-type nitride cladding layer, but it also has an advantage of maintaining thermal stability by securing thermal stability. Therefore, according to the present invention, there is an advantage that a group III n-type nitride semiconductor device having improved electrical or thermal stability and a light emitting diode device including the same can be used.

1 is a cross-sectional view of a group III n-type nitride semiconductor device according to an embodiment of the present invention.
Figure 2 shows a circular transmition line model (CTLM) pattern used for ohmic resistance measurement.
FIG. 3 shows 250 ^° C. in the case of no laser irradiation (ref) of Ti (5 nm) / Al (100 nm) / Pt (10 nm) and a laser irradiation energy of 400 mJ / cm ² , and a laser irradiation energy of 600 mJ / cm ² . Rapid Thermal annealing (RTA) N _{2 A} graph showing the current-voltage curve (IV curve) before 1min heating.
FIG. 4 shows 250 ^° C. in the case of no laser irradiation (ref) of Ti (5 nm) / Al (100 nm) / Pt (10 nm) and a laser irradiation energy of 400 mJ / cm ² and a laser irradiation energy of 600 mJ / cm ² . Rapid Thermal annealing (RTA) N _{2 A} graph showing the current-voltage curve (IV curve) after ₁ min heating.
FIG. 5 shows 250 ^° C. RTA when there is no laser irradiation (ref) of Ti (5 nm) / Al (100 nm) / Pt (10 nm) and a laser irradiation energy of 400 mJ / cm ² and a laser irradiation energy of 600 mJ / cm ² . (Rapid Thermal annealing) N ₂ 1min After heating, it is a graph showing the resistance during heat treatment in a 300 ^° C air atmosphere again.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention is capable of various modifications and various embodiments, and specific embodiments are illustrated in the drawings and described in detail in the detailed description. It is to be understood, however, that the invention is not to be limited to the specific embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

According to the present invention, there is provided a group III n-type nitride semiconductor device comprising a structure in which a nitride layer is formed on an n-type nitride cladding layer of a semiconductor device in a group III n-type nitride semiconductor device.

In addition, according to another aspect of the invention, the electrode structure (80); Nitride layer 70; an n-type nitride cladding layer 20; Nitride-based active layer 30; A p-type nitride cladding layer 40 of the metal polar surface; A reflective p-type ohmic contact electrode structure 50; And a group III n-type nitride-based semiconductor device comprising a structure in which the support substrate 60 is stacked.

The group III nitride semiconductor device may be formed of a nitride material having a compositional formula of In x Al y Ga (1-xy) N (0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ x + y ≦ 1). have. The structure in which the n-type nitride cladding layer, the nitride-based active layer, the p-type nitride cladding layer on the metal polar surface, the reflective p-type ohmic contact electrode structure, and the supporting substrate are stacked is a conventional vertical nitride-based n-type semiconductor device laminated. Structure. 1 is a cross-sectional view of a group III n-type nitride semiconductor device according to an embodiment of the present invention.

The feature of the present invention lies in that the nitride layer 70 is formed between the electrode structure 80 and the n-type nitride cladding layer 20 by laser irradiation. As a result of the laser irradiation, the nitride layer is formed while the nitrogen of the n-type nitride cladding layer is released and the nitrogen vacancies are formed in the n-type nitride cladding layer, thereby increasing the carrier concentration on the surface of the n-type nitride cladding layer. Due to the tunneling phenomenon, not only the current flows smoothly, but also the effect of securing the thermal stability and maintaining the ohmic characteristics is derived.

According to the present invention, the n-type nitride cladding layer 20 and the p-type nitride cladding layer 40 may be n-GaN and p-GaN, respectively.

In addition, the nitride based active layer 30 of the group III n-type nitride semiconductor device according to the present invention may have a single quantum well structure or a multiple quantum well structure. A quantum well structure refers to a structure in which a well shape is formed as a wall of a potential and confines electrons therein. The nitride-based active layer 30 may have a single or multiple quantum well structure.

According to the present invention, the step of sequentially growing the n-type nitride-based cladding layer 20, the nitride-based active layer 30, and the p-type nitride-based cladding layer 40 of the metal polar surface on the growth substrate; Forming a reflective p-type ohmic contact electrode structure (50) on an upper surface of the p-type nitride cladding layer (40); Forming a support substrate (60) on an upper surface of the reflective p-type ohmic contact electrode structure (50); Separating and removing the growth substrate; Forming an electrode structure (80) on an upper surface of the n-type nitride cladding layer (20); And a group III n-type nitride-based semiconductor device comprising laser irradiation on the electrode structure 80.

As described above, as the nitrogen is released from the n-type nitride cladding layer 20 by the laser irradiation, the nitride layer 70 is formed, and the nitrogen vacancies are formed in the n-type nitride cladding layer, thereby forming the n-type nitride cladding. Tunneling due to an increase in carrier concentration on the surface of the layer not only facilitates current movement but also ensures thermal stability and maintains ohmic characteristics.

According to one embodiment of the present invention, the atmosphere of the laser irradiation is not particularly limited, but may be performed in any one of air, nitrogen, argon, and vacuum atmosphere.

In addition, according to an embodiment of the present invention, the laser irradiation energy may be 300 to 900 mJ / cm ² . This is because when the laser irradiation energy is less than 300 mJ / cm ² , the nitrogen of the n-type nitride-based cladding layer does not escape, there is a problem that the nitride layer and nitrogen vacancies (N vacancy) is not formed, exceeding 900 mJ / cm ² This is because there is a problem that the electrode structure is damaged.

According to an embodiment of the present invention, the electrode structure may further include one or more barrier materials selected from the group consisting of Pt, Ti, Mo, W, and TiN. As described above, since there is a possibility that the electrode structure is oxidized when laser irradiation is performed in an air atmosphere according to one embodiment of the present invention, in this case, the barrier materials are included in the electrode structure to stably perform the reaction. can do.

According to an embodiment of the present invention, after the separating and removing the growth substrate, the method may further include forming a pattern on the n-type nitride cladding layer. This is because by forming a pattern on the nitride cladding layer, the laser can be scattered to stably perform the reaction.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be understood, however, that these examples are for illustrative purposes only and are not to be construed as limiting the scope of the present invention.

Example  One : Ti (5 nm ) / Al (100 nm ) / Pt (10 nm Specimen Fabrication and Laser Irradiation

MOCVD was used to grow 2 µm thick undoped GaN and 4 thickness n-type GaN on a sapphire substrate, and an active layer was grown thereon. Thereafter, 0.15 μm thick p-type GaN was grown on the active layer. Next, the Si substrate and the wafer were bonded using Au-Sn on the p-type GaN. Then, the sapphire substrate was irradiated with KrF laser to separate the sapphire substrate. Then, after forming a CTLM pattern using a photolithography process as shown in FIG. 2, Ti (5nm) / Al (100nm) / Pt (10nm) is deposited on the n-type GaN as an electrode structure using an E-beam evaporator. I was. Thereafter, the laser was irradiated at 400 mJ / cm ² .

Example  2 : Ti (5 nm ) / Al (100 nm ) / Pt (10 nm Specimen Fabrication and Laser Irradiation

MOCVD was used to grow 2 µm thick undoped GaN and 4 thickness n-type GaN on a sapphire substrate, and an active layer was grown thereon. Thereafter, 0.15 μm thick p-type GaN was grown on the active layer. Next, the Si substrate and the wafer were bonded using Au-Sn on the p-type GaN. Then, the sapphire substrate was irradiated with KrF laser to separate the sapphire substrate. Then, after forming a CTLM pattern using a photolithography process as shown in FIG. 2, Ti (5nm) / Al (100nm) / Pt (10nm) is deposited on the n-type GaN as an electrode structure using an E-beam evaporator. I was. Thereafter, the laser was irradiated at 600 mJ / cm ² .

Comparative example  : Ti (5 nm ) / Al (100 nm ) / Pt (10 nm Manufacture of Specimen

MOCVD was used to grow 2 µm thick undoped GaN and 4 thickness n-type GaN on a sapphire substrate, and an active layer was grown thereon. Thereafter, 0.15 μm thick p-type GaN was grown on the active layer. Next, the Si substrate and the wafer were bonded using Au-Sn on the p-type GaN. Then, the sapphire substrate was irradiated with KrF laser to separate the sapphire substrate. Then, after forming a CTLM pattern using a photolithography process as shown in FIG. 2, Ti (5nm) / Al (100nm) / Pt (10nm) is deposited on the n-type GaN as an electrode structure using an E-beam evaporator. I was.

Experimental Example  Current-voltage curve (I-V) curve Thermal stability by measurement

Samples prepared according to Examples 1, 2, and Comparative Examples were prepared, respectively, treated with 250 ° C. RTA (Rapid Thermal Annealing) N ₂ for 1 minute, and then the current-voltage curve (IV curve) before and after the heat treatment was measured. .

3 is a graph showing a current-voltage curve (IV curve) before heating 250 ^° C. RTA (Rapid Thermal annealing) N ₂ 1min for the specimens prepared by Comparative Example (ref), Example 1, and Example 2; 4 is a graph showing a current-voltage curve (IV curve) after heating 250 ^° C. RTA (Rapid Thermal annealing) N ₂ 1min for specimens prepared by Comparative Example (ref), Example 1, and Example 2. FIG.

As can be seen by comparing Figures 3 and 4, in Examples 1 and 2 there is almost no change in the resistance value even after the heat treatment, in the case of the comparative example it can be seen that the change in the resistance value is large, the ohmic characteristics are lost.

In addition, as described above, after heating the specimen prepared by Comparative Example (ref), Example 1, and Example 2 250 ^° C RTA (Rapid Thermal annealing) N ₂ 1min, heat treatment again in 300 ^° C air atmosphere It was.

As shown in FIG. 5, in the comparative example, the resistance value increased with the heat treatment time. However, in Examples 1 and 2, it was found that there was almost no change in the resistance value with the elapse of the heat treatment time.

While the present invention has been particularly shown and described with reference to specific embodiments thereof, those skilled in the art will appreciate that such specific embodiments are merely preferred embodiments and that the scope of the present invention is not limited thereby. something to do. It is therefore intended that the scope of the invention be defined by the claims appended hereto and their equivalents.

20: n-type nitride cladding layer
30: nitride based active layer
40 p-type nitride cladding layer
50: reflective p-type ohmic contact electrode structure
60: support substrate
70 nitride layer
80: electrode structure

Claims (16)

In the group III n-type nitride semiconductor device,
And a nitride layer formed of nitrogen from the n-type nitride cladding layer by laser irradiation on the n-type nitride cladding layer of the semiconductor device. The method of claim 1,
The semiconductor device includes a group having a composition formula of In x Al y Ga (1-xy) N (0≤x≤1, 0≤y≤1, 0≤x + y≤1). n-type nitride-based semiconductor device. delete Electrode structure;
A nitride layer formed from nitrogen of the n-type nitride cladding layer by laser irradiation;
n-type nitride cladding layer;
Nitride-based active layer;
A p-type nitride cladding layer of a metal polar surface;
Reflective p-type ohmic contact electrode structures; And
A light emitting diode device comprising a group III n-type nitride semiconductor device comprising a structure in which a support substrate is stacked. The method of claim 4, wherein
The semiconductor device includes a group having a composition formula of In x Al y Ga (1-xy) N (0≤x≤1, 0≤y≤1, 0≤x + y≤1). A light emitting diode device comprising an n-type nitride semiconductor device. delete The method of claim 4, wherein
The n-type nitride-based cladding layer and the p-type nitride-based cladding layer is a light emitting diode device comprising a group III n-type nitride semiconductor device, characterized in that each of n-GaN and p-GaN. The method of claim 4, wherein
The nitride-based active layer is a light emitting diode device comprising a group III n-type nitride semiconductor device, characterized in that the single quantum well (Quantum Well) structure or multiple quantum well structure. Sequentially growing an n-type nitride cladding layer of a nitrogen polar surface, a nitride active layer, and a p-type nitride cladding layer of a metal polar surface on a growth substrate;
Forming a reflective p-type ohmic contact electrode structure on an upper surface of the p-type nitride cladding layer;
Forming a support substrate on an upper surface of the reflective p-type ohmic contact electrode structure;
Separating and removing the growth substrate;
Forming an electrode structure on an upper surface of the n-type nitride cladding layer; And
Laser irradiation the electrode structure;
Method of manufacturing a light emitting diode device comprising a Group III n-type nitride semiconductor device comprising a. 10. The method of claim 9,
The laser irradiation method of manufacturing a light emitting diode device comprising a group III n-type nitride semiconductor device, characterized in that carried out in any one of air, nitrogen, argon, and a vacuum atmosphere. 10. The method of claim 9,
The laser irradiation energy is a manufacturing method of a light emitting diode device comprising a group III n-type nitride semiconductor device, characterized in that 300 to 900 mJ / cm ² . 10. The method of claim 9,
The electrode structure is a method of manufacturing a light emitting diode device comprising a group III n-type nitride semiconductor device characterized in that it further comprises at least one barrier material selected from the group consisting of Pt, Ti, Mo, W, and TiN. 10. The method of claim 9,
After separating and removing the growth substrate, a method of manufacturing a light emitting diode device comprising a group III n-type nitride semiconductor device characterized in that it further comprises the step of forming a pattern on the n-type nitride-based cladding layer. 10. The method of claim 9,
The semiconductor device includes a group having a composition formula of In x Al y Ga (1-xy) N (0≤x≤1, 0≤y≤1, 0≤x + y≤1). A method of manufacturing a light emitting diode device comprising an n-type nitride semiconductor device. 10. The method of claim 9,
The n-type nitride-based cladding layer and the p-type nitride-based cladding layer is a method of manufacturing a light emitting diode device comprising a group III n-type nitride semiconductor device, characterized in that each of n-GaN and p-GaN. 10. The method of claim 9,
The nitride-based active layer is a method of manufacturing a light emitting diode device comprising a group III n-type nitride semiconductor device, characterized in that the single quantum well (Quantum Well) structure or multiple quantum well structure.

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