JP2000101134A - Nitride semiconductor element and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form ohmic electrodes having good adhesion by a method wherein the surface of a P-type gallium nitride semiconductor crystal layer is subjected to surface treatment with a liquid having a deoxygeneration action and the ohmic electrodes are formed on the surface of the P-type gallium nitride semiconductor crystal layer. SOLUTION: A non-doped GaN layer is formed on a sapphire substrate 1 as a buffer layer 2 by an organometallic vapor growth method. An Mg-doped Al0.1Ga0.9N crystal layer (equivalent to a P-type gallium nitride semiconductor crystal layer 3) is formed on this buffer layer 2 by the organometallic vapor growth method and is used as an intermediate product. After that, gold electrodes 4 are respectively formed on the Mg-doped Al0.1G0.9N crystal layer of the intermediate product by a vacuum evaporation. In such a way, a nitride semiconductor element 5, which is provided with the buffer layer (non-doped GaN layer) 2 formed on the surface on one side of the surfaces of the substrate 1, the P-type gallium nitride semiconductor crystal layer (Mg-doped Al0.1Ga0.9N crystal layer) 3 formed on the layer 2 and the gold electrodes 4 formed on the layer 3, is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a semiconductor device having at least one p-type gallium nitride-based semiconductor crystal layer and an ohmic electrode formed on the p-type gallium nitride-based semiconductor crystal layer (hereinafter referred to as a semiconductor element). The present invention also relates to a method of manufacturing this semiconductor device, referred to as a “nitride semiconductor device”, and a nitride semiconductor device having a gold (Au) layer as the ohmic electrode.

[0002]

BACKGROUND OF THE INVENTION _{B x Al y Ga z In 1} -xyz N (x ≧
A compound semiconductor crystal represented by 0, y ≧ 0, z> 0, x + y + z ≦ 1 (in the present specification, this compound semiconductor is referred to as a “gallium nitride-based semiconductor”) is doped with Si, Ge, or the like. Since the technology for forming an n-type gallium nitride-based semiconductor crystal layer and a p-type gallium nitride-based semiconductor crystal layer doped with Mg, Zn, Cd, Be, Ca or Hg or the like has been established, semiconductor devices have been established. Has attracted attention as a material.

In particular, a light-emitting element that emits light in a blue-violet to blue wavelength range can be obtained by laminating n-type and p-type gallium nitride-based semiconductor crystal layers on a substrate. When combined with a green light-emitting element, full-color display is possible. When used as a light source for an optical recording medium, the surface recording density of the optical recording medium can be improved. When used as information transmission light, the transmission density can be improved. Therefore, the gallium nitride-based semiconductor crystal has been attracting attention as a material for a light-emitting element.

When a nitride semiconductor device is manufactured, an n-type gallium nitride-based semiconductor crystal layer and a p-type gallium nitride-based semiconductor crystal layer are often stacked on a substrate.
Usually, at least one electrode is formed on the p-type gallium nitride-based semiconductor crystal layer.

In order to obtain a high performance nitride semiconductor device, it is desirable to form an electrode in ohmic contact with the underlying semiconductor crystal layer (hereinafter, this electrode is referred to as an "ohmic electrode"). It is. As a material for an ohmic electrode formed on a p-type gallium nitride based semiconductor crystal layer, gold (Au) has been conventionally known.

However, the gold (Au) electrode has poor adhesion to the p-type gallium nitride based semiconductor crystal layer, and is easily peeled off during the operation in the next step. Particularly, in the wire bonding step, almost 100% of the gold (Au) electrode is peeled off.

For this reason, an electrode having high adhesion to the p-type gallium nitride-based semiconductor crystal layer and making ohmic contact with the p-type gallium nitride-based semiconductor crystal layer has been developed, and some proposals have already been made. ing.

For example, JP-A-6-275868 discloses that (1) a Cr layer or a Ni layer is formed on a p-type gallium nitride based semiconductor crystal layer having a specific carrier concentration, and then the Cr layer or the Ni layer is formed. A method of forming an ohmic electrode by annealing, and (2) a Cr-Ni alloy layer or Au, Pt, Mo, T on a p-type gallium nitride based semiconductor crystal layer having a specific carrier concentration.
A method of forming an ohmic electrode by forming an alloy layer of at least one metal selected from i, In, and Ga and Cr or Ni and then annealing the alloy layer is disclosed.

Further, Japanese Patent Application Laid-Open No. 7-94782 discloses that
A gallium nitride-based semiconductor light-emitting device in which an ohmic electrode and a bonding electrode are separately formed and a p-layer has a light-emitting observation surface side is disclosed. In this gallium nitride-based semiconductor light emitting device, as shown in FIG. 6, an n-type gallium nitride-based semiconductor crystal layer 41 and a p-type gallium nitride-based semiconductor crystal layer 42 are sequentially laminated in a predetermined shape on an insulating sapphire substrate 40. Au, Pt, Al, Sn, Cr, Ti, and Al are almost completely covered on the surface of the p-type gallium nitride based semiconductor crystal layer 42.
Translucent ohmic electrode 43 made of an electrode material such as Ni
Are formed. The window 44 provided to penetrate a part of the ohmic electrode 43 has C
A bonding electrode 45 made of at least two or more of r, Al, Au or the like or Al alone is formed.
A particularly preferred ohmic electrode 43 is formed by sequentially forming a Ni layer and an Au layer on the p-type gallium nitride-based semiconductor crystal layer 42 and then performing an annealing treatment on these metal layers to form an alloy. Reference numeral 46 in FIG. 6 indicates an n-electrode formed on the n-type gallium nitride-based semiconductor crystal layer 41.

Japanese Patent Application Laid-Open No. 7-288321 discloses a method for forming an electrode having a low contact resistance on a p-type gallium nitride-based semiconductor crystal layer. A method of forming a low-resistance electrode by directly forming an alloy layer containing Mg and / or Zn, and (2) an Au layer, a Mg layer and / or a Zn layer on a p-type gallium nitride-based semiconductor crystal layer. After sequentially forming the layers, these Au layers and Mg layers and / or Z
A method for forming a low-resistance electrode by alloying an n-layer by annealing treatment is disclosed.

[0011]

It has been difficult to simply form a single metal electrode on a p-type gallium nitride based semiconductor crystal layer to satisfy both ohmic properties and adhesion.

A method has been proposed in which an ohmic electrode is obtained by forming an alloy layer having a predetermined composition and performing annealing, but annealing is an essential step.

A method of sequentially laminating a plurality of single metal thin films according to the composition of an alloy electrode and then alloying the single metal thin films by annealing has been proposed. However, such a method requires a number of steps. Increases, and it takes a relatively long time to form an alloy electrode, and the productivity tends to decrease.

Similarly, in order to form an ohmic electrode made of a single Ni or Cr on the p-type gallium nitride based semiconductor crystal layer, the Ni layer or the Cr layer is first formed, and then the Ni layer or the Cr layer is annealed. Since it must be treated, it takes a relatively long time to form it, and the productivity tends to decrease.

[0015] Even when an electrode for ohmic contact and an electrode for bonding are formed on the p-type gallium nitride based semiconductor crystal layer, the number of steps is increased and it takes a relatively long time to form a target electrode. And productivity tends to decrease.

A first object of the present invention is to provide a semiconductor device having a p-type gallium nitride-based semiconductor crystal layer and an ohmic electrode formed on the p-type gallium nitride-based semiconductor crystal layer, wherein the ohmic electrode is hardly peeled off. It is an object of the present invention to provide a method for manufacturing a nitride semiconductor device that can easily obtain a nitride semiconductor device.

A second object of the present invention is to provide a semiconductor device having a p-type gallium nitride-based semiconductor crystal layer and a gold (Au) electrode in ohmic contact with the p-type gallium nitride-based semiconductor crystal layer. An object of the present invention is to provide a nitride semiconductor device in which a gold (Au) electrode is hard to peel off.

[0018]

According to one aspect of the present invention, there is provided a method of manufacturing a nitride semiconductor device including at least one p-type gallium nitride-based semiconductor crystal layer, the method comprising: A step of subjecting at least a portion of the surface of the semiconductor crystal layer where an ohmic electrode is to be formed to a surface treatment with a liquid having a deoxidizing effect, and forming an ohmic electrode on the surface of the surface-treated p-type gallium nitride-based semiconductor crystal layer And a method of manufacturing a nitride semiconductor device.

According to another aspect of the invention, at least one
A method for manufacturing a nitride semiconductor device including a p-type gallium nitride-based semiconductor crystal layer, wherein a native oxide film is formed on at least a portion of the surface of the p-type gallium nitride-based semiconductor crystal layer where an ohmic electrode is to be formed. And a step of forming an ohmic electrode on the surface of the surface-treated p-type gallium nitride based semiconductor crystal layer.

According to still another aspect of the present invention, at least one n-type gallium nitride-based semiconductor crystal layer and a gold (Au) electrode in ohmic contact with the p-type gallium nitride-based semiconductor crystal layer are provided. A nitride semiconductor element having a high adhesion of the gold (Au) electrode to the p-type gallium nitride-based semiconductor crystal layer such that peeling does not occur in a wire bonding step.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to examples and comparative examples.

First, a non-doped GaN layer (thickness: 3 μm) as a buffer layer is formed on a sapphire substrate by metal organic chemical vapor deposition, and a 1 μm thick film is formed on the buffer layer.
Of Mg-doped Al _0.1 Ga _0.9 N crystal layers (corresponding to a p-type gallium nitride based semiconductor crystal layer) by metal organic chemical vapor deposition to obtain a total of ten intermediate products.

Next, the individual intermediate products were immersed in aqua regia (concentrated nitric acid 1: concentrated hydrochloric acid 3 in volume ratio) at a liquid temperature of 20 ° C., whereby Mg-doped Al0.1 G in these intermediate products was obtained.
a0.9 N crystal layer was subjected to surface treatment. The immersion time at this time is 60 seconds, 180 seconds, 300 seconds, 4 seconds for each intermediate product.
The time was set to 20 seconds or 600 seconds so that two intermediate products having the same immersion time were obtained.

After the above surface treatment, each intermediate product is subjected to a rinsing treatment using ultrapure water within 30 seconds, for example, for about 15 seconds, and immediately thereafter, these intermediate products are treated with isopropyl alcohol (H ₂ O content of 0.1%). 01% or less).

Thereafter, the Mg-doped Al _0.1
Forty-nine gold (Au) electrodes each having a diameter of 150 μm and a thickness of 0.6 μm were formed on the Ga _0.9 N crystal layer by vacuum evaporation. Thus, as shown in FIG. 1, the sapphire substrate 1 and the buffer layer (non-doped GaN layer) 2 formed on one side of the sapphire substrate 1
And a p-type gallium nitride based semiconductor crystal layer (Mg-doped Al _0.1 Ga _0.9 N crystal layer) 3 formed on buffer layer 2
A total of 10 nitride semiconductor elements 5 having the following and 49 gold (Au) electrodes 4 formed on the p-type gallium nitride-based semiconductor crystal layer 3 were obtained. At this time, all the intermediate products were immersed in the above isopropyl alcohol until immediately before the formation of the gold (Au) electrode 4.

Each of the nitride semiconductor devices thus manufactured was subjected to the following adhesion test I and adhesion test II. Table 1 shows the results.

(1) Adhesion test I Each of the nitride semiconductor elements was covered with an adhesive sheet (Icross tape manufactured by Mitsui Toatsu Chemicals, Inc.) so as to cover all the gold (Au) electrodes. The adhesive sheet was peeled off from the end, and the gold (A
u) Count the number of electrodes.

(2) Adhesion Test II As shown in FIG. 2, a gold wire 10 having a diameter of 25 μm can be connected to each gold (Au) electrode 4 constituting the nitride semiconductor element 5 by a ball bonding method. Test whether or not. The bonding conditions at this time were as follows: the stage temperature was 80 ° C., the pressurizing time was 50 to 70 ms, and the tool (capillary 11 (see FIG. 2)) was moved up and moved 2 mm. As long as the gold wire 10 can be connected by the bonding operation,
Gold (Au) to which the gold wire 10 could not be connected
The number of electrodes 4 is counted. Note that among the members illustrated in FIG. 2, those that are common to the members illustrated in FIG. 1 are given the same reference numerals as used in FIG. 1.

As a comparative example, a total of two nitride semiconductor devices were manufactured under the same conditions as in the above embodiment except that the surface treatment with aqua regia was not performed. The adhesion test I and the adhesion test II were performed under exactly the same conditions as in the examples. The results are also shown in Table 1.

[0030]

[Table 1] * 1: Indicates the percentage of the gold (Au) layer peeled off together with the adhesive sheet. * 2: Indicates the percentage of the gold (Au) layer to which the gold wire could not be connected.

As shown in Table 1, Mg-doped Al _0.1
By subjecting the Ga _0.9 N crystal layer to a surface treatment with aqua regia, a gold (Au) layer is simply formed on the Mg-doped Al _0.1 Ga _0.9 N crystal layer, and high adhesion can be achieved without annealing. It is possible to form a gold (Au) electrode underneath. In the case of the above embodiment, the effect of the surface treatment with aqua regia is fully exhibited even if the treatment time is about 1 minute, but by setting the treatment time to about 5 minutes or more, extremely high adhesion can be obtained. Above the gold (Au)
It becomes possible to form an electrode.

FIG. 3A shows the IV characteristics of the gold electrode formed on the surface of the p-type gallium nitride based semiconductor layer subjected to the aqua regia treatment. A clean ohmic characteristic in which the current changes linearly with the change in voltage is obtained.

The current-voltage characteristics between any two gold (Au) electrodes formed on the Mg-doped Al _0.1 Ga _0.9 N crystal layer irrespective of the presence or absence of heat treatment (alloying heat treatment) after the electrode formation is shown in FIG. Ohmic properties as shown in (A) were exhibited.

FIG. 3 (B) shows p without aqua regia treatment.
Of the gold electrode formed on the surface of the p-type gallium nitride based semiconductor layer
The V characteristic is shown. The rising portion of the current has a curved characteristic, and cannot be said to be an ohmic characteristic to a strict meaning. Also, the resistance is high.

Although it has not been confirmed what kind of phenomenon has occurred on the surface of the gallium nitride-based semiconductor due to the surface treatment with aqua regia, it is highly likely that the natural oxide film formed on the surface has been removed. Then, if the natural oxide film is removed from the gallium nitride based semiconductor surface, an electrode having excellent adhesion and ohmic properties can be formed.

As described above, the present invention has been described with reference to Examples and Comparative Examples, but the present invention is not limited to the above Examples.

For example, in the above embodiment, p
-Type gallium nitride based semiconductor crystal layer (Mg-doped Al_0.1G
a_0.9N crystal layer) has been surface-treated, but limited to aqua regia
Of hydrochloric acid such as fuming hydrochloric acid, hydrochloric acid-hydrogen peroxide mixture, etc.
Ga such as liquid or nitric acid liquid _TwoO_ThreeAgainst deoxygenation
It is expected that similar effects can be obtained if the liquid has
Wear. Among the liquids that have a deoxidizing effect, hydrochloric acid-based liquids
Preferred, especially aqua regia.

In the preparation of aqua regia, concentrated nitric acid 1: concentrated hydrochloric acid 3 is generally used in a volume ratio, but the effect is recognized even in a wider mixing range. Similarly, the volume ratio of hydrochloric acid to aqueous hydrogen peroxide in the mixed solution of hydrochloric acid and aqueous hydrogen peroxide is preferably 1: 1. However, the effect may be obtained even if the volume ratio is other than 1: 1.

The treatment time of a surface treatment using a liquid having a deoxidizing effect (hereinafter, this surface treatment is referred to as "surface treatment I") varies depending on the type of liquid used and its temperature. In any case where any of the liquids exemplified in (1) and (2) is used, the gallium nitride-based semiconductor crystal is not substantially adversely affected by excessive processing, regardless of the temperature of the liquid.

After the surface treatment I, it is practically preferable to perform a rinsing treatment as in the above-described embodiment. This rinsing treatment is preferably performed in a short time using ultrapure water or pure water having an oxygen content of about 10 ppm or less. For example, when the oxygen content at 25 ° C. is approximately 5 pp
b, the processing time is set to about 30 seconds or less, and the pure water having an oxygen content of 8 ppm or less (electrical resistivity of 15 MΩ or more) is set to about 15 seconds.
It is preferable to set the time to seconds or less. Rinsing treatment using a liquid having a high oxygen content or rinsing treatment for a long time is not preferable because a natural oxide film may be formed on the surface of the p-type gallium nitride-based semiconductor crystal layer.

After performing the rinsing process, it is preferable to shift to the step of forming an electrode within as short a time as possible. As in the example, immediately after the rinsing treatment, at least a p-type gallium nitride-based semiconductor crystal layer (a p-type gallium nitride-based semiconductor crystal layer on which an electrode is to be formed) is placed in isopropyl alcohol or another dehydrating liquid. It is preferable to immerse and keep it as it is until electrode formation. As a dehydrating liquid other than isopropyl alcohol, for example, methanol, ethanol, acetone and the like can be used. H ₂ O in dehydrating liquid
The content is preferably about 0.01% or less. Since the dehydrating liquid needs to be volatilized in a later step, the liquid having high volatility is preferable as the dehydrating liquid, and isopropyl alcohol is particularly preferable from such a viewpoint.

After performing the above-described surface treatment I, rinsing treatment and, if necessary, immersion treatment in a dehydrating liquid, an electrode is formed on the p-type gallium nitride-based semiconductor crystal layer, whereby the electrode material is produced. Even if only gold (Au) is used, the electrode can be formed on the p-type gallium nitride-based semiconductor crystal layer with high adhesion. Moreover, surface treatment with a liquid having a deoxidizing effect,
The rinsing process and the immersion process in a dehydrating liquid can be easily performed in a cleaning process conventionally performed when manufacturing a nitride semiconductor device.

Accordingly, gold (Au),
Platinum (Pt), iridium (Ir), palladium (P
By using a single metal such as d) alone, it becomes possible to easily form an ohmic electrode that is difficult to peel off on the p-type gallium nitride-based semiconductor crystal layer without performing an annealing treatment. At this time, the electrode made of a single metal is formed by forming a desired single metal layer by a method such as a vacuum evaporation method or a sputtering method, and then, if necessary, etching the single metal layer into a predetermined shape. be able to.

For example, when gold (Au) is used as the electrode material, the p-type nitride layer can be formed simply by simply forming a gold (Au) layer having a desired shape without performing post-treatment such as annealing. A gold (Au) electrode having high adhesion to the gallium-based semiconductor crystal layer can be obtained so as not to cause peeling in the wire bonding step.

When gold (Au) is used as the electrode material, gold (Au) is formed on the p-type gallium nitride-based semiconductor crystal layer.
u) After the electrode is formed, A is further added on the gold (Au) electrode.
By forming a layer made of a single metal or alloy such as l, tin (Sn) or the like, the bonding properties of the entire electrode can be further improved.

By performing the above-described surface treatment I, even if an alloy electrode is formed on the p-type gallium nitride-based semiconductor crystal layer in the same manner as in the prior art, the alloy electrode can be applied to the p-type gallium nitride-based semiconductor crystal layer. The adhesion will be improved.

When a natural oxide film is formed on the surface of the p-type gallium nitride based semiconductor crystal layer, the natural oxide film can be eliminated by performing surface treatment I.
Therefore, the same effect as the surface treatment I is obtained by removing the natural oxide film formed on the surface of the p-type gallium nitride based semiconductor crystal layer on which the electrode is to be formed by the surface treatment ( Hereinafter, this surface treatment is referred to as “surface treatment II”).

The surface treatment II includes (1) a treatment for etching and removing a natural oxide film formed on the surface of the p-type gallium nitride-based semiconductor crystal layer (hereinafter, this treatment is referred to as “surface treatment IIa”). And (2) a treatment for deoxidizing the natural oxide film formed on the surface layer of the p-type gallium nitride-based semiconductor crystal layer (hereinafter, this treatment is referred to as “surface treatment IIb”).

Examples of the surface treatment IIa include wet etching, dry etching, milling, and sputtering. On the other hand, examples of the surface treatment IIb include a treatment with a gas having a deoxidizing effect, and the above-described surface treatment I.

When the surface treatment IIa is performed,
When performing b, if there is a possibility that a residue remains on the surface,
Thereafter, if necessary, it is preferable to perform a rinsing treatment in the same manner as in the surface treatment I, and further to perform an immersion treatment in a dehydrating liquid.

Although the nitride semiconductor device manufactured in the above-described embodiment has only one gallium nitride-based semiconductor crystal layer except for the buffer layer, the nitride semiconductor device has at least one layer of p-type. And a p-type gallium nitride-based semiconductor crystal layer and at least one ohmic electrode formed on the p-type gallium nitride-based semiconductor crystal layer based on the above method. It can be appropriately selected according to the intended use of the nitride semiconductor device and the like.

For example, when the intended nitride semiconductor element is a light emitting element, whether the light emitting element is a light emitting diode or a semiconductor laser, or a display light emitting element, or a communication light emitting element. The layer configuration is appropriately selected depending on whether there is, or whether the element is a surface-emitting element or an edge-emitting element.

At this time, components other than the ohmic electrode formed on the p-type gallium nitride-based semiconductor crystal layer can be formed by a known method. It can be appropriately selected in consideration of properties and the like.

For example, an i-type or non-doped gallium nitride-based semiconductor crystal layer, an n-type gallium nitride-based semiconductor crystal layer, and a p-type gallium nitride-based semiconductor crystal layer are formed by a molecular beam epitaxy method, a gas source molecular beam epitaxy method, or an organic metal. It can be formed by a method such as a vapor phase growth method and a halide vapor phase growth method.

As shown in FIG. 4, a buffer layer 21 is formed on a sapphire substrate 20, and n
After sequentially stacking the p-type gallium nitride based semiconductor crystal layer 22 and the p-type gallium nitride based semiconductor crystal layer 23,
The p-type gallium nitride-based semiconductor crystal layer 22 and the p-type gallium nitride-based semiconductor crystal layer 23 are etched into a predetermined shape, and then a p-electrode 24 is formed on the p-type gallium nitride-based semiconductor crystal layer 23 based on the method of the present invention. Then, by forming the n-electrode 25 on the n-type gallium nitride-based semiconductor crystal layer 22, a surface-emitting light-emitting diode 26 that emits blue light can be obtained. The order of forming the p-electrode 24 and the n-electrode 25 is appropriately selected.

As shown in FIG. 5, a buffer layer 31, an n-type gallium nitride-based semiconductor crystal layer 32, an active layer 34, and a p-type gallium nitride-based semiconductor crystal layer 36 are sequentially stacked on a sapphire substrate 30. The layer above the n-type gallium nitride-based semiconductor crystal layer 32 is etched into a predetermined shape, and then a p-electrode 37 is formed on the p-type gallium nitride-based semiconductor crystal layer 36 based on the above-described method. By forming the n-electrode 38 on the system semiconductor crystal layer 32, a semiconductor laser 39 having a double hetero structure that emits blue-violet light can be obtained. The order of forming the p-electrode 37 and the n-electrode 38 is appropriately selected.

In manufacturing a nitride semiconductor device, it is preferable to use a sapphire substrate as a substrate for forming a gallium nitride-based semiconductor crystal layer, but it is also possible to use a silicon carbide substrate, spinel, or the like. When a conductive substrate such as a silicon carbide substrate is used, a p-electrode is formed on the p-type gallium nitride-based semiconductor crystal layer, and if necessary, the back surface of the conductive substrate (the gallium nitride-based semiconductor crystal layer is The n-electrode may be formed on the surface opposite to the surface on which it is formed). When a silicon carbide substrate is used, it is preferable that the plane direction of the surface on which the gallium nitride-based semiconductor crystal layer is to be formed be (0001).

[0058]

As described above, according to the present invention,
Since it becomes easy to form an ohmic electrode with high adhesion on the p-type gallium nitride based semiconductor crystal layer, it is possible to provide a nitride semiconductor device with high productivity.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view schematically showing a nitride semiconductor device manufactured in an example.

FIG. 2 is a cross-sectional view schematically showing an adhesion test II performed in Examples and Comparative Examples.

FIG. 3 is a graph showing an example of a current-voltage characteristic when a current is applied to the nitride semiconductor device manufactured in the example.

FIG. 4 is a cross-sectional view schematically showing an example of a light emitting diode which is one of the nitride semiconductor devices manufactured based on the method of the present invention.

FIG. 5 is a sectional view schematically showing an example of a semiconductor laser which is one of the nitride semiconductor devices manufactured based on the method of the present invention.

FIG. 6 is a sectional view schematically showing an example of a nitride semiconductor device manufactured by a conventional method.

[Explanation of symbols]

1,20,30 ... sapphire substrate, 2,21,31 ...
Buffer layer 3, Mg-doped Al0.1 Ga0.9 N crystal layer 4, gold (Au) electrode 10, gold wire 11,
... capillary, 22, 32 ... n-type gallium nitride based semiconductor crystal layer, 23,36 ... p-type gallium nitride based semiconductor crystal layer, 24,37 ... p electrode, 25,38 ... n electrode,
26: light emitting diode, 33: n-type cladding layer,
34: active layer, 35: p-type cladding layer, 39: semiconductor laser

Claims (9)

[Claims] 1. A method of manufacturing a nitride semiconductor device including at least one p-type gallium nitride-based semiconductor crystal layer, wherein at least an ohmic electrode is formed on a surface of the p-type gallium nitride-based semiconductor crystal layer. A method for manufacturing a nitride semiconductor device, comprising: a step of surface-treating a portion to be formed with a liquid having a deoxidizing effect; and a step of forming an ohmic electrode on the surface of the surface-treated p-type gallium nitride-based semiconductor crystal layer. 2. The method according to claim 1, wherein a hydrochloric acid-based, sulfuric acid-based or nitric acid-based liquid or hydrofluoric acid is used as the liquid having a deoxygenating action. 3. The method according to claim 1, wherein aqua regia is used as the deoxygenating liquid. 4. The method according to claim 1, wherein the liquid having a deoxygenating action is p-type.
After performing the step of performing a surface treatment on the p-type gallium nitride-based semiconductor crystal layer, performing a rinsing treatment on the surface-treated p-type gallium nitride-based semiconductor crystal layer, and then performing at least the surface treatment until an ohmic electrode is formed. The method according to any one of claims 1 to 3, wherein the surface of the p-type gallium nitride based semiconductor crystal layer is immersed in a dehydrating liquid. 5. The method according to claim 4, wherein isopropyl alcohol is used as the dehydrating liquid. 6. The method according to claim 1, wherein a gold (Au) electrode is formed as the ohmic electrode. 7. A method of manufacturing a nitride semiconductor device including at least one p-type gallium nitride-based semiconductor crystal layer, wherein at least an ohmic electrode is formed on a surface of the p-type gallium nitride-based semiconductor crystal layer. A method for manufacturing a nitride semiconductor device, comprising: a step of performing a surface treatment for removing a natural oxide film on a portion to be formed, and a step of forming an ohmic electrode on the surface of the surface-treated p-type gallium nitride-based semiconductor crystal layer . 8. The method according to claim 7, wherein a gold (Au) electrode is formed as the ohmic electrode. 9. At least one n-type gallium nitride-based semiconductor crystal layer and a gold (Au) electrode in ohmic contact with the p-type gallium nitride-based semiconductor crystal layer, wherein the gold (Au) A nitride semiconductor device, wherein the adhesion of an electrode to the p-type gallium nitride-based semiconductor crystal layer is so high that no peeling occurs in a wire bonding step.