JP2002353506A - Semiconductor light-emitting element and manufacturing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor light-emitting element which has a low forward voltage, emits light uniformly over the entire light emission region, and has excellent reliability as a semiconductor light-emitting element, which is so structured that a translucent electrode containing Pd is formed on a light emission translucent surface and light is guided out through the translucent electrode. SOLUTION: This semiconductor light-emitting element has at least a 1st conductivity-type gallium nitride compound semiconductor layer and a 2nd conductivity-type gallium nitride compound semiconductor layer on a substrate. The element is further equipped with the translucent electrode which is formed on the surface of the 2nd conductivity-type gallium nitride compound semiconductor layer, a conductivity-type film which continuously covers a region adjacent to the circumference of the flank of the translucent electrode on the top and flank of the translucent electrode and the surface of the 2nd conductivity-type gallium nitride compound semiconductor layer, and a pad electrode which is formed on the surface of the 2nd conductivity-type gallium compound semiconductor layer on the conductivity-type film respectively.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gallium nitride based compound semiconductor light emitting device and a method of manufacturing the same, and more particularly, to a gallium nitride based compound semiconductor light emitting device (laser and light emitting diode) capable of emitting light in a blue region to an ultraviolet region. LED), and more particularly to an electrode structure of a light-emitting element having a gallium nitride-based compound semiconductor layer as a light-emitting light-transmitting surface.

[0002]

2. Description of the Related Art FIG. 9 shows an electrode structure of a conventional gallium nitride compound semiconductor light emitting device. In FIG. 9, an n-type contact layer 20 is formed on an insulating sapphire substrate 100.
0, an active layer 300, a p-type cladding layer 400, and a p-type contact layer 410 are laminated in this order.
A first layer 500 (such as palladium Pd) and a second layer 600 (a transparent conductive film containing an oxide) are formed on the surface, and a pad electrode is further formed on the exposed first layer 500. 700 are formed, and the n-electrode 800
Gallium nitride-based compound semiconductor light emitting device formed on the mold contact layer 200 is disclosed in, for example, Japanese Patent Application Laid-Open No. 9-1299.
No. 19 discloses this.

[0003]

The electrode structure shown in FIG.
On the mold contact layer 410, a first layer 500 (palladium Pd) and a second layer 600 having the same shape as the first layer
(A transparent conductive film containing an oxide) is formed, and the pad electrode 700 is formed on the exposed first layer 500 (palladium Pd).

Here, the first layer 500 is a light-transmitting metal thin film.
Formed on the surface of With this configuration, when a current is externally supplied to the gallium nitride-based compound semiconductor light emitting device from the pad electrode 700, the pad electrode 700
It has been found that the light emission in the vicinity of is particularly stronger than the other light emitting regions. This is because the ohmic contact right under the pad electrode is better than in other regions, and the current supplied from the outside hardly spreads through the first layer 500, so that only the vicinity of the pad electrode emits light. It is thought that it is. Furthermore, for the above reason, the current supplied from the outside does not uniformly flow through the second layer 600 (the transparent conductive film containing an oxide) in the configuration of the pad electrode. Since the current becomes non-uniform, and the current flows only in the vicinity of the pad electrode, the area through which the current flows decreases, the forward voltage of the semiconductor light emitting element increases, and the heat generation of the semiconductor light emitting element increases. This is a cause of deteriorating the reliability of the semiconductor light emitting device.

[0005]

According to the present invention, at least a first conductive type gallium nitride-based compound semiconductor layer and a second conductive type gallium nitride-based compound semiconductor layer are provided on a substrate. A translucent electrode formed on the surface of the type gallium nitride-based compound semiconductor layer, and on the translucent electrode,
A conductive film that continuously covers a side surface thereof and a region adjacent to the periphery of the side surface on the surface of the second conductive type gallium nitride based compound semiconductor layer, and a surface of the second conductive type gallium nitride based compound semiconductor layer or There is provided a gallium nitride-based compound semiconductor light emitting device, comprising: a pad electrode formed on a conductive film.

That is, according to the present invention, a region of the light-transmitting electrode, the side surface thereof, and the region adjacent to the periphery of the side surface on the surface of the second conductivity type gallium nitride-based compound semiconductor layer are continuously formed of a conductive type film. By covering and providing a pad electrode on the conductive type film or on the surface of the second conductive type gallium nitride-based compound semiconductor layer, the current supplied from the outside via the pad electrode is dispersed so as to flow as uniformly as possible. West,
Thereby, a uniform light emitting pattern can be obtained.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention,
When a translucent electrode containing at least Pd (palladium) formed on the surface of the conductive type gallium nitride-based compound semiconductor layer is used as an ohmic electrode [or an ohmic electrode, and the current-voltage characteristics of the semiconductor-metal contact are linear. Electrode (metal)], a conductive film is used as a transparent conductor film, and a pad electrode has a layered structure including a current blocking layer containing no Pd (palladium). While making the current easier to flow, it prevents the current flow directly under the pad electrode, thereby dispersing the current flow throughout the light emitting device, preventing the forward voltage of the light emitting device from increasing, and making the current flow more uniform. A light emission pattern can be obtained. In addition to the above Pd, Ni (nickel), Co
(Cobalt) etc. in the translucent electrode,
The same ohmic properties as described above can be obtained.

[0008] Here, the laminated structure of the pad electrode provided with a current blocking layer means a laminated structure provided as a single layer with a layer capable of preventing the flow of current immediately below the pad electrode. Comprises a pad electrode composed of a laminate composed of at least two layers, and as a layer in contact with the second-conductivity-type gallium nitride-based compound semiconductor layer, a metal having a non-ohmic contact with the surface of the semiconductor layer. , For example, Pd
(Palladium) -free, Ti (titanium), Ta (tantalum), Cr (chromium), Mo (molybdenum), Al
(Aluminum) or W (tungsten) may be used. The layer on the opposite side that does not come into contact with the semiconductor layer includes a layer made of Au (gold).

Further, according to the present invention, the pad electrode is provided on a part of the gallium nitride-based compound semiconductor layer of the second conductivity type, and the translucent electrode is provided around the part of the gallium nitride-based compound semiconductor layer. Each formed on the surface of the compound semiconductor layer,
That is, a transparent conductor film as the conductive type film is formed on the translucent electrode, a part of the translucent electrode and the transparent conductor film are removed, and a second conductive type gallium nitride-based compound is formed. When the surface of the semiconductor layer is exposed and the pad electrode is formed thereon, it is possible to prevent light from being emitted by the light-emitting layer immediately below (under) the pad electrode without current being injected immediately below the pad electrode, As a result, a current is uniformly diffused in the translucent electrode and the transparent conductor film, and a gallium nitride-based compound semiconductor light emitting device having a uniform light emitting pattern and a small forward voltage is obtained.

Further, the light-transmitting electrode is formed on the surface of the second conductivity type gallium nitride-based compound semiconductor layer, a part of the light-transmitting electrode is removed, and the pad electrode is formed in the removed region. When the transparent conductor film is formed so as to cover the translucent electrode and the pad electrode, the pad electrode is formed on the surface of the second conductivity type gallium nitride-based compound semiconductor layer. Immediately below the electrode, it is possible to prevent light from being emitted from the light-emitting layer immediately below (below) the pad electrode without current being injected. Therefore, current is uniformly diffused into the translucent electrode and the transparent conductor film. Thus, a gallium nitride-based compound semiconductor light emitting device having a uniform light emitting pattern and a small forward voltage can be obtained. Further, since the transparent conductor film is formed on the pad electrode, the pad electrode can be prevented from peeling off.

FIG. 8 is an enlarged view schematically showing a cross section of an electrode according to the present invention. As shown in FIG. 8, the thickness of the layer constituting the lowermost layer of the pad electrode is set to be thicker than the thickness of the translucent electrode, and the uppermost layer of the pad electrode is formed of Au.
Since the setting is made so that (gold) does not contact the light-transmitting electrode, the reaction between Au and the light-transmitting electrode can be prevented, and the thickness of the light-transmitting electrode near the pad electrode becomes thinner and higher. A uniform light emitting pattern can be obtained without resistance.

Further, the pad electrode is formed on the surface of the gallium nitride-based compound semiconductor layer of the second conductivity type, and the pad electrode and the second conductivity type are formed around the pad electrode so that the pad electrode and the translucent electrode do not come into contact with each other. When the light-transmitting electrode is formed on the surface of the gallium nitride-based compound semiconductor layer and the transparent conductor film is formed so as to cover the pad electrode and the light-transmitting electrode, the second conductive type gallium nitride-based Since the pad electrode is formed directly on the surface of the compound semiconductor layer, no current is injected immediately below the pad electrode, and no light is emitted from the light-emitting layer immediately below (below) the pad electrode. A gallium nitride-based compound semiconductor light-emitting device having a uniform light-emitting pattern and a small forward voltage can be obtained because current is uniformly diffused in the translucent electrode and the transparent conductor film. Furthermore, since the pad electrode and the light-transmitting electrode of the thin film are formed without contact, when performing a heat treatment to obtain ohmic contact of the light-transmitting electrode,
The uppermost layer Au (gold) constituting the pad electrode reacts with the translucent electrode containing Pd, and the resistance of the reaction region becomes higher than that of the other translucent electrode regions. A phenomenon in which the light emission pattern becomes slightly dark can be prevented, and a gallium nitride-based compound semiconductor light emitting device having a uniform light emission pattern can be obtained.

Further, the light-transmissive electrode is formed on the surface of the second conductivity type gallium nitride-based compound semiconductor layer, and a dielectric insulating film is formed in a partial region on the light-transmissive electrode. And on the dielectric insulating film, the transparent conductive film is formed so as to cover, further, a pad electrode is formed on the transparent conductive film, and further, when the pad electrode is formed above the dielectric insulating film, Since the dielectric insulating film is formed below the pad electrode, it is possible to prevent light from being emitted from the light-emitting layer immediately below (below) the pad electrode without current being injected immediately below the pad electrode. For this reason,
The injected current uniformly flows through the transparent conductor film, and then the current is injected from the translucent electrode to the second conductivity type gallium nitride based compound semiconductor layer, so that a uniform light emission pattern and a small forward voltage are obtained. A gallium compound semiconductor light emitting device is obtained.

Further, the dielectric insulating film is formed on the surface of the second conductivity type gallium nitride based compound semiconductor layer, the light-transmitting electrode is formed on the dielectric insulating film, and the light-transmitting electrode is formed on the light-transmitting electrode. When the transparent conductor film is formed so as to cover it, a pad electrode is formed on the transparent conductor film, and the pad electrode is formed above the dielectric insulating film, the second electrode below the pad electrode is formed. Since the dielectric insulating film is formed on the surface of the conductive gallium nitride-based compound semiconductor layer, light is emitted from the light-emitting layer immediately below (below) the pad electrode without current being injected immediately below the pad electrode. Can be prevented. For this reason, the injected current uniformly flows through the transparent conductor film, and then the second current flows from the light-transmitting electrode.
Since a current is injected into the conductive gallium nitride-based compound semiconductor layer, a gallium nitride-based compound semiconductor light-emitting device having a uniform light emission pattern and a small forward voltage can be obtained.

Further, the light-transmissive electrode is formed on the surface of the second conductivity type gallium nitride-based compound semiconductor layer, a part of the light-transmissive electrode is removed, and a part of the light-transmissive electrode is removed. The transparent conductor film is formed so as to cover the formed region, a pad electrode is further formed on the transparent conductor film, and the pad electrode is formed above a part of the light-transmitting electrode that has been removed. Then, since the transparent conductor film is formed on the surface of the gallium nitride-based compound semiconductor layer of the second conductivity type, the injected current does not flow to the region where the transparent conductor film is formed. Immediately below the pad electrode, no current is injected, and no light is emitted from the light-emitting layer immediately below (below) the pad electrode. Therefore, the injected current uniformly flows from the transparent conductor film to the translucent electrode, so that a gallium nitride-based compound semiconductor light emitting device having a uniform light emission pattern and a small forward voltage can be obtained.

Further, the pad electrode on the transparent conductor film forms a laminate, and the contact side that contacts the transparent conductor film is Ti (titanium), Ta (tantalum), Cr (chromium), Mo ( Molybdenum), Al (aluminum), W
(Tungsten), non-contact side layer (top layer) is Au (gold)
By using the metal on the side that comes into contact with the transparent conductive film, the adhesion between the transparent conductive film and the pad electrode is improved, the peeling of the pad electrode is reduced, and thus the gallium nitride The production yield of the compound semiconductor light emitting device can be improved.

Here, it is preferable to use a transparent conductor film as a conductive type film as a protective film as a translucent electrode containing Pd. As a material of the transparent conductor film, In ₂
At least one of O ₃ , SnO ₂ , ZnO, Cd ₂ SnO ₄ and CdSnO ₃ is used. In the case of In ₂ O ₃ , one of Sn, W, Mo, Zr, Ti, Sb, F and the like is used as a dopant. In the case of SnO ₂ , one of Sb, P, Te, W, Cl, F and the like is used as a dopant. In the case of Cd ₂ SnO ₄ , Ta is used as a dopant. In the case of ZnO, Al, In,
One of B, F, etc. is used. For the formation of the transparent conductor film, a method generally known as a method for forming a transparent conductor film in this field, such as an evaporation method, a sputter method, and a CVD method, can be used.

According to another aspect of the present invention, there is provided a method comprising:
Laminating at least a first conductivity type gallium nitride-based compound semiconductor layer and a second conductivity type gallium nitride-based compound semiconductor layer; Forming an electrode, and so as to continuously cover a part of the surface of the second conductivity type gallium nitride-based compound semiconductor layer adjacent to the light-transmitting electrode, the side wall thereof and the periphery of the light-transmitting electrode, Forming a conductive type film and forming a part of a laminated portion of the light-transmitting electrode and the conductive type film or a conductive type film above the second conductive type gallium nitride-based compound semiconductor layer. A step of previously removing a part of the light-transmitting electrode and a pad on the surface of the second conductivity type gallium nitride-based compound semiconductor layer exposed by removing a part of the laminated portion or a part of the light-transmitting electrode. Step of forming electrodes Method for producing a gallium nitride-based compound semiconductor light-emitting device comprising a can provide.

The substrate is not particularly limited as long as it is generally used as a substrate for a light emitting device.
For example, semiconductor substrates such as silicon and germanium, Si
Any substrate such as a compound semiconductor substrate such as Ge, SiC, GaAs, and GaP, and an insulating substrate such as glass, sapphire, quartz, and resin can be used. Among them, an insulating substrate is preferable.

The semiconductor layers, that is, the first conductivity type gallium nitride-based compound semiconductor layer and the second conductivity type gallium nitride-based compound semiconductor layer are formed by a known method, for example, a metal organic chemical vapor deposition (MOCVD) method, a molecular beam crystal. Growth (MBE) method, CV
It can be formed by Method D or the like. The p-type and n-type impurities for forming the pn junction may be doped simultaneously with the formation of the semiconductor layer, or may be doped by ion implantation or thermal diffusion after the formation of the semiconductor layer.

Further, the translucent electrode of the present invention is formed mainly directly connected to the semiconductor layer, and constitutes a current injection region. Further, the light-transmitting electrode can be an electrode that can efficiently inject current into the current injection region and can efficiently extract light emitted from the semiconductor layer (for example, a light transmittance of about 30 to 100%). . In addition, it may be formed from over the current injection region to over the current blocking layer. The material of the light-transmitting electrode is not particularly limited as long as the material has the above-described light transmittance. For example, nickel, aluminum, gold, copper, silver, titanium, tantalum, lead, palladium,
Examples thereof include metals such as platinum and Co, and transparent conductive materials such as SnO2, ZnO, and ITO. These materials may be formed as either a single-layer film or a laminated film. The film thickness can be appropriately adjusted so as to have an appropriate light-transmitting property when the above-mentioned material is used. For example, the film thickness of the light-transmitting electrode is preferably about 20 nm or less.

Hereinafter, the present invention will be described with reference to specific embodiments shown in the drawings.
This will be described in detail based on the form. In this specification,
The gallium nitride-based semiconductor is, for example, In_xAl_yG
a_{1- xy}Including N (0 ≦ x, 0 ≦ y, x + y ≦ 1)
And In this specification, a semiconductor light-emitting element emits light.
Including diodes and semiconductor lasers.

(Embodiment 1) FIG. 1 is a schematic sectional view of an electrode of a gallium nitride-based compound semiconductor light emitting device manufactured as Embodiment 1 of the present invention. In FIG. 1, reference numeral 1 denotes a sapphire substrate, 2 denotes an n-type gallium nitride-based compound semiconductor layer as a first conductivity type, 3 denotes a gallium nitride-based compound semiconductor light emitting layer, and 4 denotes a p-type gallium nitride-based compound as a second conductivity type. The semiconductor layer, 5 is a translucent electrode, 6 is a transparent conductor film as a conductive type film, 7 (including 71) is a P-side pad electrode, 8 is an Au wire connection, and 9 is an n-type electrode. .

The electrode forming process according to the first embodiment of the present invention will be described in detail. (1) On a sapphire substrate 1, an n-type gallium nitride-based compound semiconductor layer 2, a gallium nitride-based compound semiconductor light-emitting layer 3,
The p-type gallium nitride-based compound semiconductor layers 4 are sequentially stacked.
A translucent electrode 5 and a transparent conductor film 6 are formed on the p-type gallium nitride based compound semiconductor layer 4. Here, the translucent electrode 5
Formed a 3 nm-thick Pd, applied a resist to form a light emitting region, and used a normal photo-etching process.
The translucent electrode 5 is etched with a mixed solution of nitric acid and hydrochloric acid. The transparent conductor film 6 formed so as to cover the translucent electrode 5 uses Sn as a dopant in In ₂ O ₃ and has a thickness of 400 nm. Next, a resist is applied in order to form a protection region by the transparent conductor film 6, and the transparent conductor film 6 is removed by an ordinary photo-etching process using the etching solution (iron chloride-based solution). Here, the formation region of the transparent conductor film 6 is formed not only on the surface of the light-transmitting electrode 5 but also on the side surface, and further, on the surface of the p-type gallium nitride-based compound semiconductor layer 4 on which the light-transmitting electrode 5 is not formed. It is formed continuously so as to cover the top. Further, a resist is applied to form the opening region 51, and a part of the transparent conductor film 6 is etched with an iron chloride-based solution using a normal photoetching process. Etching is performed with a mixture of nitric acid and hydrochloric acid to form an opening 51 exposing the surface of the p-type gallium nitride-based compound semiconductor layer 4 to a diameter of 80 μm. Since the Ti (titanium) 71 is formed to be thicker than the Pd film thickness as the pad electrodes 7 and 71 in the exposed regions, the thickness is formed to be 15 nm.
Next, Au (gold) 7 is formed to a thickness of 500 nm.

(2) Next, using the resist as a mask for dry etching, etching is performed by a dry etching method until the surface of the n-type gallium nitride-based compound semiconductor layer 2 is exposed.

(3) Next, an n-type electrode 9 is formed on the surface of the n-type gallium nitride compound semiconductor layer 2. The n-type electrode 9 is made of Al (having a thickness of 150 nm) and Ti (having a thickness of 1).
5 nm). Next, in order to provide electrical contact between the pad electrode and the outside, the pad electrode 7 for P side is used.
Then, the Au wire 8 is connected on the n-type electrode 9.

Here, by forming Ti71 which is a non-ohmic contact with the p-type gallium nitride based compound semiconductor layer 4 and is a part of the pad electrode in the opening 51, a current flows in the region of the Ti71. The injected current flows uniformly through the transparent conductor film 6 and also flows uniformly through the light-transmitting electrode underneath, and no current flows immediately below the P-side pad electrode 7. No light is emitted only directly under the pad electrode 7. Therefore, a uniform light emitting pattern can be obtained in the light emitting region. Further, since the current does not concentrate directly below the P-side pad electrode 7, it is possible to prevent the forward voltage of the present light emitting element from increasing.

(Embodiment 2) FIG. 2 is a schematic sectional view of an electrode of a gallium nitride based compound semiconductor light emitting device manufactured as Embodiment 2 of the present invention. In FIG. 2, 1 is a sapphire substrate, 2 is an n-type gallium nitride compound semiconductor layer, 3 is a gallium nitride compound semiconductor light emitting layer,
4 is a p-type gallium nitride-based compound semiconductor layer, 5 is a translucent electrode, 7 (including 71) is a P-side pad electrode, 6 is a transparent conductor film, 8 is a connection portion of an Au wire, and 9 is an n-type. Electrodes.

The electrode manufacturing process of the present invention will be described in detail. (1) On an sapphire substrate 1, an n-type gallium nitride-based compound semiconductor layer 2, a gallium nitride-based compound semiconductor light-emitting layer 3,
The p-type gallium nitride-based compound semiconductor layers 4 are sequentially stacked.
Transparent electrode 5 on p-type gallium nitride based compound semiconductor layer 4
To form The translucent electrode 5 is formed of Pd with a thickness of 2 nm.
A resist is applied to form a light-emitting region, and the light-transmitting electrode 5 is etched with the etching solution using a normal photoetching process. Next, the translucent electrode 5 is etched using the above-mentioned etching solution (mixed solution of nitric acid and hydrochloric acid) to expose the surface of the p-type gallium nitride-based compound semiconductor layer 4 to a diameter of 80 μm to form an opening 51. I do.

Next, as the P-side pad electrodes 7 and 71 in the exposed region, the Hf (hafnium) 71 is formed to be thicker than the Pd film thickness, so that the thickness is formed to 15 nm, and then Au (gold) is formed. 7 is formed to a thickness of 500 nm. Its diameter was 100 μm.

Next, the transparent conductor film 6 formed so as to cover the P-side pad electrodes 7 and 71 and the translucent electrode 5 is made of In.
Sn is used as a dopant for ₂ O ₃ , and its thickness is 300
It is formed to a thickness of nm. Next, a resist is applied in order to form a protection region by the transparent conductor film 6, and the transparent conductor film 6 is removed by the above-mentioned etching solution using a normal photo-etching process. Here, the formation region of the transparent conductor film 6 is:
It is formed continuously so as to cover not only the surface of the light-transmitting electrode 5 but also the side surface and the surface of the p-type gallium nitride-based compound semiconductor layer 4 where the light-transmitting electrode 5 is not formed.

(2) Next, using the resist as a mask for dry etching, etching is performed by a dry etching method until the surface of the n-type gallium nitride-based compound semiconductor layer 2 is exposed.

(3) Next, an n-type electrode 9 is formed on the surface of the n-type gallium nitride compound semiconductor layer 2. The n-type electrode 9 is made of Al (having a thickness of 200 nm) and Hf (having a thickness of 5 nm).
nm).

Next, an Au wire 8 is connected to the pad electrode 7 for the P side and the electrode 9 for the N-type in order to provide electrical contact between the pad electrode and the outside. Here, by forming Hf71 which is a non-ohmic contact with the p-type gallium nitride based compound semiconductor layer 4 and is a part of the pad electrode in the opening 51, current hardly flows in the Hf71 region. Therefore, no current flows immediately below the P-side pad electrode 7, and the injected current flows uniformly through the transparent conductive film and the translucent electrode. As a result, a uniform light emitting pattern can be obtained in the light emitting region formed by the translucent electrode. Furthermore, since the current does not concentrate directly below the P-side pad electrode 7, the forward voltage of the present light emitting element does not increase. Further, the transparent conductor film 6 is formed on the P-side pad electrode 7, and the pressing action prevents the P-side pad electrode 7 from peeling off during wire bonding, thereby improving the production yield.

(Embodiment 3) FIG. 3 is a schematic sectional view of an electrode of a gallium nitride-based compound semiconductor light-emitting device manufactured as Embodiment 3 of the present invention. 3, 1 is a sapphire substrate, 2 is an n-type gallium nitride compound semiconductor layer, 3 is a gallium nitride compound semiconductor light emitting layer,
4 is a p-type gallium nitride-based compound semiconductor layer, 5 is a translucent electrode, 7 (including 71) is a P-side pad electrode, 6 is a transparent conductor film, 8 is a connection portion of an Au wire, and 9 is an n-type. Electrodes.

The electrode manufacturing process of the present invention will be described in detail. (1) On an sapphire substrate 1, an n-type gallium nitride-based compound semiconductor layer 2, a gallium nitride-based compound semiconductor light-emitting layer 3,
The p-type gallium nitride-based compound semiconductor layers 4 are sequentially stacked.
Transparent electrode 5 on p-type gallium nitride based compound semiconductor layer 4
To form The translucent electrode 5 is formed of Pd with a thickness of 2 nm.
Next, the light emitting region and the opening region 51 are formed on the P-type potassium nitride-based compound semiconductor layer 4 by a normal photo etching process.
To form The translucent electrode 5 is etched with the etching solution to form a light emitting region and an opening region 51 on the surface of the p-type gallium nitride based compound semiconductor layer 4 to have a diameter of 100 μm.
Expose. A P-side pad electrode 7 (including 71) having a diameter of 80 μm is formed in the exposed region.

Here, the translucent electrode 5 and the P-side pad electrode are not in contact with each other. The P-side pad electrode is formed of Ti (titanium) 71 with a thickness of 30 nm, and A
u (gold) 7 is 400 nm thick. A transparent conductor film 6 formed to cover the surface of the P-side pad electrode, the translucent electrode 5 and the p-type gallium nitride-based compound semiconductor layer 4
Forms a Sn layer as a dopant in In ₂ O ₃ and has a thickness of 300 nm.

Next, a resist is applied to form a protected area by the transparent conductive film 6, and the transparent conductive film 6 is removed by the above-mentioned etching solution using a usual photo-etching process. Here, the formation region of the transparent conductor film 6 is formed not only on the surface of the light-transmitting electrode 5 but also on the side surface and on the surface of the p-type gallium nitride-based compound semiconductor layer 4 where the light-transmitting electrode 5 is not formed. Is formed continuously so as to cover the entire surface.

(2) Next, using the resist as a mask for dry etching, etching is performed by dry etching until the surface of the n-type gallium nitride-based compound semiconductor layer 2 is exposed.

(3) Next, an n-type electrode 9 is formed on the surface of the n-type gallium nitride-based compound semiconductor layer 2. The n-type electrode 9 is made of Al (having a thickness of 150 nm) and Ti (having a thickness of 1).
5 nm). Next, in order to provide electrical contact between the pad electrode and the outside, the pad electrode 7 for P side is used.
The Au wire 8 is connected on the N-type electrode 9.

Here, since the Au of the P-side pad electrode 7 and the Pd of the translucent electrode 5 are not in contact with each other, the thickness of Pd in the region in contact with Au does not become thin. In the vicinity of the P-side pad electrode 7, there is no high-resistance region, and current is uniformly injected into the translucent electrode 5. For this reason, the light emitting pattern becomes uniform in the light emitting region formed by the translucent electrode 5. Although the cause of the decrease in the thickness of Pd when it comes into contact with Au is not clearly understood, it is considered that a reaction occurs in which Pd is drawn into Au.

Therefore, the Au of the P-side pad electrode 7 and the Pd of the translucent electrode 5 do not come into contact with each other.
Au is connected to Pd of the translucent electrode 5 by a transparent conductive film 6. Further, by forming Ti71, which is a non-ohmic contact and is a part of the pad electrode, in the opening 51, current does not easily flow in the region of the Ti71, and therefore, immediately below the P-side pad electrode 7, , No current flows, and the injected current flows uniformly through the transparent conductor film and the translucent electrode, and does not emit light only under the P-side pad electrode 7.
A uniform light emitting pattern can be obtained in the light emitting region formed by the above, and since the current does not concentrate directly under the P-side pad electrode 7, it is possible to prevent the forward voltage of the present light emitting element from increasing.

(Embodiment 4 of the Present Invention) FIG. 4 is a schematic sectional view of an electrode of a gallium nitride-based compound semiconductor light emitting device manufactured as Embodiment 4 of the present invention. In FIG. 4, reference numeral 60 denotes a conductive GaN substrate, 2 denotes an n-type gallium nitride-based compound semiconductor layer, 3 denotes a gallium nitride-based compound semiconductor light-emitting layer, 4 denotes a p-type gallium nitride-based compound semiconductor layer, 5 denotes a translucent electrode, Reference numeral 7 (including 71) denotes a P-side pad electrode, 6 denotes a transparent conductor film, 8 denotes a connection portion of an Au wire, and 9 denotes an n-type electrode.

The electrode manufacturing process according to the fourth embodiment of the present invention will be described in detail. (1) An n-type gallium nitride-based compound semiconductor layer 2, a gallium nitride-based compound semiconductor light-emitting layer 3, and a p-type gallium nitride-based compound semiconductor layer 4 are sequentially stacked on a conductive GaN substrate 60. The translucent electrode 5 is formed on the p-type gallium nitride-based compound semiconductor layer 4. The translucent electrode 5 is formed of Pd with a thickness of 3.5 nm. Next, in order to form the light emitting region and the opening 51, the light transmitting electrode 5 is etched using a normal photo etching process. The translucent electrode 5 is etched using the etching solution to form a light emitting region, and the surface of the p-type gallium nitride based compound semiconductor layer 4 is exposed to a diameter of 80 μm. Next, the P-side pad electrodes 7 and 71 having a diameter of 100 μm were
Since the thickness 71 is formed to be thicker than the Pd film thickness, the thickness is formed to 30 nm, and then Au7 is formed to a thickness of 500 nm. Next, a transparent conductor film is formed so as to cover the P-side pad electrodes 7 and 71 and the translucent electrode 5. The transparent conductor film 6 uses Sn as a dopant for In ₂ O ₃ ,
The thickness is formed to be 300 nm.

Next, a resist is applied to form a protection region by the transparent conductive film 6, and the transparent conductive film 6 is removed with the above-mentioned etching solution by using a usual photo-etching process. Here, the formation region of the transparent conductor film 6 is not only on the surface of the light-transmitting electrode 5 but also on the side surface, and further, on the surface of the p-type gallium nitride-based compound semiconductor layer 4 where the light-transmitting electrode 5 is not formed. It is formed continuously so as to cover the top.

(2) Next, an n-type electrode 9 is formed on the back surface of the conductive GaN substrate 60. The n-type electrode 9 is made of Al
(Thickness: 500 nm) and Hf (thickness: 5 nm) are used. Next, an Au wire 8 is connected on the P-side pad electrode 7 in order to make the pad electrode 7 electrically contact with the outside. Here, in addition to the features described in Embodiment 1, electrodes can be formed above and below by using a conductive substrate, and the manufacturing method is further simplified.

(Fifth Embodiment of the Present Invention) FIG. 5 is a schematic sectional view of an electrode of a gallium nitride-based compound semiconductor light emitting device manufactured as a fifth embodiment of the present invention. In FIG. 5, 1 is a sapphire substrate, 2 is an n-type gallium nitride-based compound semiconductor layer, 3 is a gallium nitride-based compound semiconductor light-emitting layer,
4 is a p-type gallium nitride-based compound semiconductor layer, 5 is a translucent electrode, 73 is a dielectric insulating film, 6 is a transparent conductor film, and 7 (72
) Is a P-side pad electrode, 8 is a connection portion of an Au wire, and 9 is an n-type electrode.

(1) An n-type gallium nitride-based compound semiconductor layer 2, a gallium nitride-based compound semiconductor light emitting layer 3, and a p-type gallium nitride-based compound semiconductor layer 4 are sequentially laminated on a sapphire substrate 1. The translucent electrode 5 is formed on the p-type gallium nitride-based compound semiconductor layer 4. The translucent electrode 5 has Pd of 3 nm.
It is formed thick. Next, in order to form a light emitting region, the light transmitting electrode 5 is etched with the etching solution using a normal photo etching process. A dielectric insulating film SiO ₂ 73 is formed thereon to a thickness of 100 nm. Next, a transparent conductor film 6 is formed so as to cover the translucent electrode 5 and the dielectric insulating film 73. The transparent conductor film 6 uses Sn as a dopant for In ₂ O ₃ and has a thickness of 300 nm.

Next, Mo (molybdenum) 72 is formed to a thickness of 20 nm on the surface of the transparent conductive film 6 as P-side pad electrodes 7 and 72, and then Au (gold) 7 is formed to a thickness of 500 n.
m is formed. The dielectric insulating film 73, the P-side pad electrode 7
And 72 each had a diameter of 100 μm. Next, a resist is applied in order to form a protection region by the transparent conductive film 6, and the transparent conductive film 6 is removed by the above-mentioned etching solution using a normal photo-etching process. Here, the formation region of the transparent conductor film 6 is not only on the surface of the light-transmitting electrode 5 but also on the side surface, and further, on the surface of the p-type gallium nitride-based compound semiconductor layer 4 where the light-transmitting electrode 5 is not formed. It is formed continuously so as to cover the top.

(2) Next, using the resist as a mask for dry etching, etching is performed by a dry etching method until the surface of the n-type gallium nitride-based compound semiconductor layer 2 is exposed.

(3) Next, an n-type electrode 9 is formed on the surface of the n-type gallium nitride compound semiconductor layer 2. The n-type electrode 9 is made of Al (having a thickness of 150 nm) and Hf (having a thickness of 3 nm).
nm). Next, an Au wire 8 is connected on the P-side pad electrode 7 and the N-type electrode 9 in order to provide electrical contact between the pad electrode and the outside.

Here, since the dielectric insulating film 73 is formed immediately below the P-side pad electrode 7, no light is emitted below the P-side pad electrode 7, and the current is made uniform via the transparent conductor film 6. Since the current is injected into the translucent electrode 5 uniformly, the light emitting region emits light uniformly. Further, Mo is formed on 72 to improve the adhesion between the P-side pad electrode 7 and the transparent conductor film 6 and the adhesion is improved, whereby the P-side pad electrode is not peeled off, and the manufacturing yield is improved. There is.

(Embodiment 6) FIG. 6 is a schematic sectional view of an electrode of a gallium nitride-based compound semiconductor light emitting device manufactured as Embodiment 6 of the present invention. In FIG. 6, 1 is a sapphire substrate, 2 is an n-type gallium nitride-based compound semiconductor layer, 3 is a gallium nitride-based compound semiconductor light-emitting layer,
4 is a p-type gallium nitride compound semiconductor layer, 73 is a dielectric insulating film, 5 is a translucent electrode, 6 is a transparent conductor film, and 7 (72
) Is a P-side pad electrode, 8 is a connection portion of an Au wire, and 9 is an n-type electrode.

(1) An n-type gallium nitride-based compound semiconductor layer 2, a gallium nitride-based compound semiconductor light emitting layer 3, and a p-type gallium nitride-based compound semiconductor layer 4 are sequentially laminated on a sapphire substrate 1. A dielectric insulating film 73 is formed to a thickness of 100 nm on the p-type gallium nitride-based compound semiconductor layer 4, and then formed using a normal photo-etching process using hydrofluoric acid with an etchant so that the diameter remains at 100 μm. I do. Next, on the p-type gallium nitride-based compound semiconductor layer 4 and the dielectric insulating film 73, a 4 nm-thick Pd is formed as the translucent electrode 5. In order to form a light emitting region, the light transmitting electrode 5 is etched with the etching solution using a normal photo etching process. Next, a transparent conductor film 6 is formed so as to cover the translucent electrode 5. The transparent conductor film 6 uses Sn as a dopant for In ₂ O ₃ and has a thickness of 2 nm.
It is formed to a thickness of 00 nm. Next, a resist is applied in order to form a protection region by the transparent conductor film 6, and the transparent conductor film 6 is removed by the above-mentioned etching solution using a normal photo-etching process.

Next, Ta (tantalum) 72 is formed to a thickness of 30 nm on the surface of the transparent conductor film 6 as P-side pad electrodes 7 and 72 so as to be disposed on the dielectric insulating film 73.
u (gold) 7 is formed to a thickness of 500 nm. Each of the P-side pad electrodes 7 and 72 on the dielectric insulating film 73 has a diameter of 8
It was set to 0 μm. Here, the formation region of the transparent conductor film 6 is:
Not only on the surface of the translucent electrode 5, but also on the side,
It is formed continuously so as to cover the surface of the p-type gallium nitride-based compound semiconductor layer 4 where the light-transmitting electrode 5 is not formed.

(2) Next, using the resist as a mask for dry etching, etching is performed by a dry etching method until the surface of the n-type gallium nitride-based compound semiconductor layer 2 is exposed.

(3) Next, an n-type electrode 9 is formed on the surface of the n-type gallium nitride-based compound semiconductor layer 2. The n-type electrode 9 is made of Al (having a thickness of 150 nm) and Hf (having a thickness of 5 nm).
nm). Next, an Au wire 8 is connected on the P-side pad electrode 7 and the N-type electrode 9 in order to provide electrical contact between the pad electrode and the outside. Here, since the dielectric insulating film 73 is formed immediately below the P-side pad electrode 7 and directly below the translucent electrode 5, no light is emitted below the P-side pad electrode 7, and the injected current is transparent. The light uniformly flows into the translucent electrode 5 via the conductor film 6, and uniformly emits light in a light emitting region formed by contact of the translucent electrode 5 and the p-type gallium nitride-based compound semiconductor layer 4. Further, by forming Ta on 72 in order to improve the adhesion between the P-side pad electrode 7 and the transparent conductor film 6, there is a feature that the P-side pad electrode is not peeled off and the production yield is improved.

(Embodiment 7 of the Present Invention) FIG. 7 is a schematic sectional view of an electrode of a gallium nitride-based compound semiconductor light emitting device manufactured as Embodiment 7 of the present invention. 7, reference numeral 60 denotes a conductive Si substrate, 2 denotes an n-type gallium nitride-based compound semiconductor layer, 3 denotes a gallium nitride-based compound semiconductor light-emitting layer, 4 denotes a p-type gallium nitride-based compound semiconductor layer, 5 denotes a translucent electrode, Reference numeral 6 denotes a transparent conductor film, 7 (including 72) denotes a P-side pad electrode, 8 denotes a connection portion of an Au wire, and 9 denotes an n-type electrode.

(1) An n-type gallium nitride-based compound semiconductor layer 2, a gallium nitride-based compound semiconductor light-emitting layer 3, and a p-type gallium nitride-based compound semiconductor layer 4 are sequentially stacked on a Si substrate 60. Next, Pd is formed to a thickness of 3 nm on the p-type gallium nitride-based compound semiconductor layer 4 as the translucent electrode 5. In order to form the light-emitting region and the opening 51, the light-emitting region is formed by etching using the above-described etching solution by using a normal photo-etching process, and then the light-transmitting electrode 5 has a diameter of 80 μm near the center thereof. Opening 51 is formed. A transparent conductor film 6 is formed so as to cover the translucent electrode 5 and the opening 51. The transparent conductor film 6 is formed of In ₂ O ₃ using Sn as a dopant, and has a thickness of 150 nm.

Next, a resist is applied to form a protection region with the transparent conductor film 6, and the transparent conductor film 6 is removed by the above-mentioned etching solution using a usual photo-etching process. Next, W (tungsten) 72 is formed to a thickness of 20 nm as P-side pad electrodes 7 and 72 on the surface of the transparent conductor film 6 so as to be disposed on the opening 51, and
u7 is formed to a thickness of 500 nm. The diameter of each of the P-side pad electrodes 7 and 72 on the opening 51 was 80 μm. Here, the formation region of the transparent conductor film 6 is not only on the surface of the light-transmitting electrode 5 but also on the side surface, and further, on the surface of the p-type gallium nitride-based compound semiconductor layer 4 where the light-transmitting electrode 5 is not formed. It is formed continuously so as to cover the top.

(2) Next, an n-type electrode 9 is formed on the back surface of the Si substrate 60. The n-type electrode 9 is made of Al (thickness 1).
50 nm). Next, in order to provide electrical contact between the pad electrode 7 and the outside, A
u-wire 8 is connected.

As described above, by forming the non-ohmic transparent conductor film 6 in the opening 51, that is, on the surface of the p-type gallium nitride-based compound semiconductor layer 4, the non-ohmic transparent conductor film 6 is formed immediately below the P-side pad electrode 7. No current flows, and no light is emitted immediately below the P-side pad electrode 7, so that a uniform light emitting pattern can be obtained in the light emitting region. Embodiment 5
Alternatively, instead of using the dielectric insulating film of 6 as a current blocking layer, the transparent conductive film 6 can be used as a current blocking layer, so that a semiconductor light emitting device having a current blocking type structure can be easily realized, and furthermore its manufacturing method. Has the feature that it is simpler.

Here, Embodiments 1, 2, 3, 4,
In 5, 6, and 7, the n-type electrode 9 may be formed on the n-type gallium nitride-based compound semiconductor layer 2 around the light emitting region. Further, in the first to seventh embodiments, an In ₂ O ₃ film, Au, Ti, Ta, and Mo are formed using a normal sputtering method.
Pd, Al, Hf, and W were each formed using an electron beam evaporation method. As described above, the gallium nitride-based compound semiconductor light-emitting device structure has been described as a light-emitting device having a homostructure. However, a gallium nitride-based compound semiconductor light-emitting device can be applied to any structure such as a double hetero structure, a single hetero structure, and a quantum well structure. Needless to say.

[0064]

According to the present invention, the conductive type film is continuously formed on the light-transmitting electrode, the side surface thereof, and a part of the surface of the second conductive type gallium nitride-based compound semiconductor layer adjacent to the light-transmitting electrode. By providing a pad electrode on the conductive type film, current supplied from the outside via the pad electrode is dispersed so that it flows as uniformly as possible, thereby obtaining a uniform light emitting pattern. it can.

Further, according to the present invention, by providing a current blocking structure in which current does not easily flow directly under the pad electrode provided on the light emitting surface, only the light directly under the pad electrode does not emit light intensely, and the entire light emitting surface can be made more uniform. Gallium nitride-based compound semiconductor light-emitting device with excellent reliability because a light-emitting pattern can be obtained and current does not flow only directly under the pad electrode, thereby preventing an increase in forward voltage of the light-emitting device. Can be realized.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of an electrode of a gallium nitride-based compound semiconductor light emitting device according to a first embodiment of the present invention.

FIG. 2 is a schematic sectional view of an electrode of a gallium nitride-based compound semiconductor light emitting device according to a second embodiment of the present invention.

FIG. 3 is a schematic sectional view of an electrode of a gallium nitride-based compound semiconductor light emitting device according to a third embodiment of the present invention.

FIG. 4 is a schematic sectional view of an electrode of a gallium nitride-based compound semiconductor light emitting device according to a fourth embodiment of the present invention.

FIG. 5 is a schematic sectional view of an electrode as Embodiment 5 of the gallium nitride-based compound semiconductor light emitting device of the present invention.

FIG. 6 is a schematic sectional view of an electrode as Embodiment 6 of the gallium nitride based compound semiconductor light emitting device of the present invention.

FIG. 7 is a schematic sectional view of an electrode of a gallium nitride-based compound semiconductor light emitting device according to a seventh embodiment of the present invention.

FIG. 8 is an enlarged view schematically showing a cross section of an electrode of the gallium nitride based compound semiconductor light emitting device of the present invention.

FIG. 9 is a schematic sectional view of an electrode structure of a conventional gallium nitride based compound semiconductor light emitting device.

[Explanation of symbols]

 1, 100: sapphire substrate 60: n-type GaN substrate or Si substrate 2, 200: n-type gallium nitride-based compound semiconductor layer 3, 300: gallium nitride-based compound semiconductor light emitting layer 4, 400: p-type gallium nitride-based compound semiconductor layer 410: p-type gallium nitride compound semiconductor contact layer 5, 500: translucent electrode 51: opening of translucent electrode 6, 600: transparent conductor film 7, 700: p-side pad electrode 73: dielectric insulating film 8 Au wire connection 9 n-side pad electrode

Continued on the front page (72) Inventor Daikaku Kimura 22-22 Nagaike-cho, Abeno-ku, Osaka City, Osaka F-term (reference) 5F041 AA05 AA43 CA40 CA83 CA88 CA93 CB03 5F073 AA61 CA01 CB03 CB22 DA23

Claims (10)

[Claims] A first conductive type gallium nitride-based compound semiconductor layer and a second conductive type gallium nitride-based compound semiconductor layer; and a second conductive type gallium nitride-based compound semiconductor layer on a surface of the substrate. A light-transmitting electrode formed on the light-transmitting electrode, a conductive type that continuously covers a region adjacent to the periphery of the side on the surface of the light-transmitting electrode, the side surface thereof, and the surface of the second conductive type gallium nitride-based compound semiconductor layer. And a pad electrode formed on the surface of the second conductivity type gallium nitride-based compound semiconductor layer or on the conductivity type film. 2. The light-transmitting electrode is an ohmic electrode containing at least Pd, the conductive film is a transparent conductor film, and the pad electrode is formed on the surface of the second conductive gallium nitride-based compound semiconductor layer. The gallium nitride-based compound semiconductor light emitting device according to claim 1, further comprising a current blocking layer formed and containing no Pd. 3. A pad electrode is formed on a part of the gallium nitride-based compound semiconductor layer of the second conductivity type, and a light-transmitting electrode is formed on the second gallium nitride-based compound semiconductor layer.
2. The gallium nitride-based compound semiconductor light emitting device according to claim 1, wherein the gallium nitride-based compound semiconductor light-emitting device is formed on the surface of the conductive gallium nitride-based compound semiconductor layer and adjacent to the periphery of the part. 4. The gallium nitride based compound semiconductor light emitting device according to claim 3, wherein the conductive type film further covers the pad electrode. 5. A pad electrode is formed on the surface of the second conductivity type gallium nitride-based compound semiconductor layer, and the light-transmitting electrode is formed on the second conductive type gallium nitride-based compound semiconductor layer.
A conductive type film was formed on the surface of the conductive type gallium nitride-based compound semiconductor layer and around the pad electrode so as not to contact the pad electrode, and a conductive type film was formed to cover the pad electrode and the translucent electrode. The gallium nitride-based compound semiconductor light emitting device according to claim 1, wherein: 6. A dielectric insulating film formed between a portion on the light-transmitting electrode and a conductive type film, wherein the pad electrode is on the conductive type film, and The gallium nitride-based compound semiconductor light emitting device according to claim 1, wherein the light emitting device is formed above. 7. A dielectric insulating film formed between a portion on the surface of the second conductivity type gallium nitride based compound semiconductor layer and the light transmitting electrode, wherein the pad electrode is formed on the conductive type film. ,
The gallium nitride-based compound semiconductor light emitting device according to claim 1, wherein the gallium nitride-based compound semiconductor light emitting device is formed above the dielectric insulating film. 8. A light-transmitting electrode is formed on a peripheral surface of the second conductive type gallium nitride-based compound semiconductor layer except for a partial surface, and a conductive type film is adjacent to the partial surface and the partial surface. 2. The gallium nitride according to claim 1, wherein the side surface of the transparent electrode is continuously covered, and the pad electrode is formed on the conductive film and above the partial surface. Based compound semiconductor light emitting device. 9. A pad electrode is formed on a conductive type film, and the contact side that contacts the conductive type film is Ti (titanium), Ta (tantalum), Cr (chromium), Mo (molybdenum), Al (aluminum) or W (tungsten) layer, non-contact side is at least two layers of Au (gold) layer
The gallium nitride-based compound semiconductor light emitting device according to any one of claims 6 to 8, wherein the gallium nitride-based compound semiconductor light emitting device is formed of a laminate having at least three or more kinds of layers. 10. A step of laminating at least a first conductivity type gallium nitride based compound semiconductor layer and a second conductivity type gallium nitride based compound semiconductor layer on a substrate, and a surface of the second conductivity type gallium nitride based compound semiconductor layer. Forming a light-transmissive electrode on the light-transmitting electrode, and forming a continuous part of the surface of the second conductivity type gallium nitride-based compound semiconductor layer on the light-transmitting electrode, the side surface thereof, and the periphery of the light-transmitting electrode Forming a conductive type film that covers the first conductive type gallium nitride-based compound semiconductor layer, a part of a laminated portion of the light-transmitting electrode and the conductive type film, or a conductive type film Removing a part of the light-transmitting electrode before forming the surface; and a surface of the second conductivity type gallium nitride-based compound semiconductor layer exposed by removing a part of the laminated portion or a part of the light-transmitting electrode. The process of forming pad electrodes on Method for producing a gallium nitride-based compound semiconductor light emitting device comprising.