JP2002151737A - Gallium nitride compound semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gallium nitride compound semiconductor device including an N-side contact electrode that comes into good ohmic contact with an N-type gallium nitride compound semiconductor layer and is high in thermal resistance and a method of manufacturing the same. SOLUTION: This gallium nitride compound semiconductor device is equipped with an N-type gallium nitride compound semiconductor layer, and an N-side contact electrode that comes into ohmic contact with the N-type gallium nitride compound semiconductor layer. The N-side contact electrode is composed of a first layer of W or Mo and a second layer of Au or Pt formed on the first layer, and the first layer is brought into ohmic contact with the N-type gallium nitride compound semiconductor layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a GaN compound semiconductor device, and more particularly to a gallium nitride compound semiconductor device using a GaN compound semiconductor having excellent heat resistance.

[0002]

2. Description of the Related Art Conventionally, in a gallium nitride-based compound semiconductor device, an electrode for ohmic contact with an n-type gallium nitride-based compound semiconductor layer is formed on a first layer made of Ti and on the first layer. And a second layer made of Al. However, since Al used as the second layer has a high ionization tendency and is easily oxidized, a barrier layer made of W or the like is further formed on the second layer, and Au or the like is formed on the barrier layer. The bonding metal layer made of was laminated.

[0003]

However, the ohmic contact electrode having the above structure has a temperature of 400.degree.
There is a problem that Al or Au is diffused by the heat treatment to a certain extent, and this has been a major factor that limits the heat-resistant temperature of the nitride semiconductor device. The present invention has been made to solve the above problems,
Provided is a gallium nitride-based compound semiconductor device having an n-side contact electrode that can obtain good ohmic contact with an n-type gallium nitride-based compound semiconductor layer and does not deteriorate even by heat treatment at about 500 ° C. and a method of manufacturing the same. The purpose is to:

[0004]

In order to solve the above-mentioned problems of the prior art, a first gallium nitride-based compound semiconductor device according to the present invention comprises an n-type gallium nitride-based compound semiconductor layer and the n-type gallium nitride-based compound semiconductor layer. In a gallium nitride-based compound semiconductor device having an n-side contact electrode in ohmic contact with a gallium nitride-based compound semiconductor layer, the n-side contact electrode is made of a first layer made of W or Mo, and the first layer And a second layer made of Au or Pt formed thereon, wherein the first layer and the n-type gallium nitride-based compound semiconductor layer make ohmic contact.

In the gallium nitride-based compound semiconductor device of the present invention thus configured, the n-side contact electrode is
Since it is configured to include the first layer made of W or Mo and the second layer made of Au or Pt thereon, n
Even if heat treatment is performed at a relatively high temperature in order to improve reliability such as ohmic heat resistance between the first layer of the side contact electrode and the n-type gallium nitride-based compound semiconductor layer, the n-side contact electrode Is hardly deteriorated. Further, since the n-side contact electrode is formed using the first layer made of W or Mo and the second layer made of Au or Pt thereon, it can be formed without containing Al. The heat resistance of the gallium nitride-based compound semiconductor device of the present invention can be improved as compared with the conventional example including the Al layer.

In the first gallium nitride-based compound semiconductor device, the thickness of the first layer is about 100 nm.
And the thickness of the second layer is preferably about 300 nm or more. By doing so, the ohmic contact between the n-side contact electrode and the n-type gallium nitride-based compound semiconductor layer can be improved, and the bonding strength can be increased.

A second gallium nitride-based compound semiconductor device according to the present invention comprises an n-type gallium nitride-based compound semiconductor layer;
A gallium nitride-based compound semiconductor device comprising the n-type gallium nitride-based compound semiconductor layer and a contact electrode in ohmic contact, wherein the n-side contact electrode is W
Or a first layer made of Mo, a second layer made of Pt formed on the first layer, and a third layer made of Au formed on the second layer. And the first
Is in ohmic contact with the n-type gallium nitride-based compound semiconductor layer.

[0008] The second gallium nitride-based compound semiconductor device of the present invention thus configured has the same function and effect as the first gallium nitride-based compound semiconductor device. That is, the n-side contact electrode is heat-treated at a relatively high temperature in order to improve the reliability such as ohmic heat resistance between the first layer made of W or Mo and the n-type gallium nitride-based compound semiconductor layer. can do. Further, in the second gallium nitride-based compound semiconductor device of the present invention, since the n-side contact electrode is configured as described above, the n-side contact electrode can be configured without containing Al. Heat resistance can be improved as compared with the examples.

In the second gallium nitride-based compound semiconductor device, the thickness of the first layer is about 100 nm.
And the total thickness of the second layer and the third layer is preferably about 300 nm or more. By doing so, the ohmic contact between the n-side contact electrode and the n-type gallium nitride-based compound semiconductor layer can be further improved, and the strength for bonding can be increased.

[0010] A third gallium nitride-based compound semiconductor device according to the present invention comprises: an n-type gallium nitride-based compound semiconductor layer;
An n-side contact electrode formed on a part of the upper surface of the n-type gallium nitride-based compound semiconductor layer; and an n-side contact electrode formed on the upper surface of the n-type gallium nitride-based compound semiconductor layer so as to be separated therefrom. Active layer, a p-type gallium nitride-based compound semiconductor layer formed on the active layer, and a p-type gallium nitride-based compound semiconductor layer formed on the p-type gallium nitride-based compound semiconductor layer.
A gallium nitride-based compound semiconductor device comprising: a p-side ohmic electrode; a p-side pad electrode formed on the p-side ohmic electrode; The side contact electrode and the p-side pad electrode are the same as each other,
It is characterized by comprising a first layer made of W or Mo, and a second layer made of Au or Pt formed on the first layer.

The third gallium nitride-based compound semiconductor device according to the present invention has the same functions and effects as the first and second gallium nitride-based compound semiconductor devices, and further has an n-side contact electrode and a p-side contact electrode. By making the layer structure common to the pad electrode, the manufacturing process can be facilitated.

A fourth gallium nitride-based compound semiconductor light emitting device according to the present invention comprises an n-type gallium nitride-based compound semiconductor layer and an n-side contact formed on a part of the upper surface of the n-type gallium nitride-based compound semiconductor layer. Electrode, an active layer formed on the upper surface of the n-type gallium nitride-based compound semiconductor layer separately from the n-side contact electrode, and a p-type gallium nitride-based compound semiconductor formed on the active layer Layers and
A gallium nitride-based compound semiconductor device comprising: a p-side contact electrode formed on the p-type gallium nitride-based compound semiconductor layer;
a p-side ohmic electrode and a p-side pad electrode formed on the p-side ohmic electrode, wherein the n-side contact electrode and the p-side pad electrode are identical to each other and are made of W or Mo, respectively. A first layer, a second layer of Pt formed on the first layer, and a third layer of Au formed on the second layer. And

The fourth gallium nitride-based compound semiconductor device according to the present invention has the same functions and effects as those of the first and second gallium nitride-based compound semiconductor devices, and further has an n-side contact electrode and a p-side By making the layer structure common to the pad electrode, the manufacturing process can be facilitated. The p-side ohmic electrode may be formed of a metal or an alloy including at least one of Au, Pt, Ni, and Pd, and may include an alloy of Ni and Au, or Ni.
It is preferably formed from an alloy consisting of Pt and Pt.

In a first method of manufacturing a gallium nitride compound semiconductor device according to the present invention, an n-type gallium nitride compound semiconductor layer, an active layer, and a p-type gallium nitride compound semiconductor layer are formed on a substrate. Sequentially growing a p-type gallium nitride-based compound semiconductor layer, and etching a part of the p-type gallium nitride-based compound semiconductor layer and the active layer to expose a part of the n-type gallium nitride-based compound semiconductor layer Forming a p-side ohmic electrode on the surface of the p-type gallium nitride-based compound semiconductor layer;
W is formed on the exposed n-type gallium nitride-based compound semiconductor layer and on the p-side ohmic electrode, respectively.
Or a step of stacking a first layer of Mo, a step of stacking a second layer of Au or Pt on the first layer, the step of stacking the p-side ohmic electrode, Heat treating the second layer at 500 ° C. or higher.

In the first manufacturing method described above, the first layer made of W or Mo and the second layer made of Au or Pt thereon are formed as the n-side contact electrode. Therefore, heat treatment can be performed at a relatively high temperature of 500 ° C. or more, and n of the first layer made of W or Mo
Reliability, such as ohmic heat resistance, of the gallium nitride-based compound semiconductor layer can be improved. Further, since the n-side contact electrode is formed using the first layer made of W or Mo and the second layer made of Au or Pt thereon, it can be formed without containing Al. As a result, a gallium nitride-based compound semiconductor device having higher heat resistance can be manufactured as compared with a conventional example including an Al layer. Further, in the above-described first manufacturing method, the n-side contact electrode and the p-side pad electrode can be manufactured by a common process using the first layer and the second layer, thereby simplifying the manufacturing process. can do.

A second method for manufacturing a gallium nitride-based compound semiconductor device according to the present invention is characterized in that an n-type gallium nitride-based compound semiconductor layer, an active layer, Sequentially growing a p-type gallium nitride-based compound semiconductor layer, and etching a part of the p-type gallium nitride-based compound semiconductor layer and the active layer to expose a part of the n-type gallium nitride-based compound semiconductor layer Forming a p-side ohmic electrode on the surface of the p-type gallium nitride-based compound semiconductor layer;
W is formed on the exposed n-type gallium nitride-based compound semiconductor layer and on the p-side ohmic electrode, respectively.
Alternatively, a step of laminating a first layer of Mo, a step of laminating a second layer of Pt on the first layer, and a step of laminating a third layer of Au on the second layer Laminating the p-side ohmic electrode and the first and second p-side ohmic electrodes.
And a step of subjecting the third layer to a heat treatment at 500 ° C. or higher.

In the above-described second manufacturing method, as the n-side contact electrode, a first layer made of W or Mo, a second layer made of Pt thereon, and a third layer made of Au thereon. The heat treatment can be performed at a relatively high temperature of 500 ° C. or more. By such a heat treatment, n of the first layer made of W or Mo
Reliability, such as ohmic heat resistance, can be achieved with respect to the gallium nitride-based compound semiconductor layer. In addition, since the n-side contact electrode is configured using the first layer, the second layer, and the third layer, it can be configured without containing Al, and can be configured including the Al layer. A gallium nitride-based compound semiconductor device having higher heat resistance than that of the conventional example described above can be manufactured. In addition, the second
According to the manufacturing method of (1), the n-side contact electrode and the p-side pad electrode can be manufactured by a common process using the first layer, the second layer, and the third layer, and the manufacturing process is simplified. can do. As described above, according to the first and second manufacturing methods according to the present invention, a gallium nitride-based compound semiconductor device having high heat resistance can be manufactured at low manufacturing cost.

[0018]

(Embodiment 1) FIG. 1 is a schematic sectional view showing the structure of a gallium nitride-based compound semiconductor device according to an embodiment of the present invention. Hereinafter, the gallium nitride-based compound semiconductor device 3 of the first embodiment will be described with reference to FIG.
0 will be described. The gallium nitride-based compound semiconductor device 30 shown in FIG. 1 is a light emitting device, and a first buffer layer 2, a second buffer layer 3, and an n-side A contact layer 4;
Third buffer layer 5, n-side multilayer film layer 6, active layer 7
And a p-side multilayer film layer 8 and a p-side contact layer 9 are laminated in this order. Then, on the n-side contact layer 4, an n-side contact electrode 20 that is in ohmic contact with the n-side contact layer 4 is formed. On the p-side contact layer 9, a p-side contact electrode 12 that is in ohmic contact with the p-side contact layer 9 on the p-side is formed.

Here, particularly in the first embodiment, n
The side contact electrode 20 includes a first layer 21 in ohmic contact with the n-side contact layer 4 and a second layer 22 formed on the first layer 21, and the first layer 21 is formed of W or The second layer 22 is made of Au or Pt. That is, the first embodiment
In the above, the n-side contact electrode 20 is made of any one of four different combinations shown in Table 1 below. Note that Pt has a property of being less eroded by dry etching than Au, and has a property of being resistant to a reactive gas, while Au has a property of having a lower resistance than Pt and being easier to bond a wire or the like. W is M
It has a higher melting point than o and higher heat resistance. The materials of the first layer 21 and the second layer 22 may be appropriately determined depending on the use of the semiconductor element to be manufactured in consideration of the above properties.

[0020]

[Table 1]

In the first embodiment configured as described above, as described above, the N-side contact electrode 20 has a W
Alternatively, the first layer 21 made of Mo makes ohmic contact with the n-side contact layer 4. In order to obtain good ohmic contact, the thickness of the first layer 21 should be 5 nm or more and 100
nm or less. When the thickness of the first layer 21 is less than 5 nm, a part of the second layer 22 comes into contact with the p-side contact layer 9 and the ohmic contact becomes poor. On the other hand, if the thickness of the first layer 21 exceeds 100 nm, the side surface of the first layer 21 is oxidized, which is not preferable.

In the n-side contact electrode 20, the second layer 22 made of Au or Pt is a layer to which a bonding wire or the like is attached, and therefore has a thickness of 300 nm or more in order to secure a certain mechanical strength. Is preferred. The upper limit of the second layer 22 is preferably 10 μm or less. This is because when the film thickness is about 10 μm, lift-off becomes difficult. Note that lift-off refers to a method of forming an electrode by masking a predetermined non-electrode-formed portion in advance on the surface of a gallium nitride-based compound semiconductor device 30, forming a metal on the entire surface, and removing the mask. means. In the n-side contact electrode 20 shown in FIG. 1, a bonding wire can be attached to the second layer 22, so that an n-side pad electrode is not separately provided. However, the present invention is not limited to this. Instead, an n-side pad electrode may be further provided on the n-side contact electrode 20.

On the other hand, in the first embodiment, a p-side electrode 12 is formed on the p-side contact layer 9. The p-side electrode 12 includes a p-side ohmic electrode 10 and a p-side pad electrode 11 formed on almost the entire surface of the p-side contact layer 9.
Consists of After the formation of the p-side ohmic electrode, a heat treatment at 500 ° C. is performed, and a good ohmic contact with the p-side contact layer 9 is realized. Here, the p-side ohmic electrode 10 is formed of a metal or an alloy containing at least one of Au, Pt, Ni, and Pd, which is a material capable of obtaining good ohmic contact with the p-type nitride semiconductor layer. You. Specifically, the p-side ohmic electrode 10 is formed of, for example, an alloy composed of Ni and Au, an alloy composed of Ni and Pt, or an alloy composed of Ni, Pt and Au. When the gallium nitride-based compound semiconductor device 30 is used face-up, the p-side ohmic electrode 10 is preferably formed of a translucent metal or alloy. When the gallium nitride-based compound semiconductor device 30 is used face-down, the p-side ohmic electrode 10 is used. Electrode 10
The material of the p-side ohmic electrode 10 may be appropriately determined in consideration of the fact that is preferably formed from a non-translucent metal or alloy. In the first embodiment, p
The side pad electrode 11 is the n-side contact electrode 2 described above.
0, so that it can be manufactured in the same process as the n-side contact electrode 20, thereby simplifying the process. That is, the p-side pad electrode 11 includes the first layer 21a and the second layer 22 formed on the first layer 21a.
a, the first layer 21a is made of W or Mo, and the second layer 22a is made of Au or Pt.

Next, a method of manufacturing the gallium nitride-based compound semiconductor device of the first embodiment will be described. (First Step) In a first step, an n-type gallium nitride-based compound semiconductor layer, an active layer, and a p-type gallium nitride-based compound semiconductor layer, each made of a gallium nitride-based compound semiconductor, are sequentially grown on the substrate 1. More specifically, a first buffer layer 2, a second buffer layer 3, an n-side contact layer 4, and an n-type gallium nitride-based compound semiconductor layer,
Growing a third buffer layer 5 and an n-side multilayer film layer 6;
After the active layer 7 is grown on the n-side multilayer film layer 6, p-type gallium nitride-based compound semiconductor layers are further formed.
The side multilayer film layer 8 and the p-side contact layer 9 are sequentially grown.

(Second Step) In the second step, a light-emitting portion is formed in order to expose a part of the n-type gallium nitride-based compound semiconductor layer (n-side contact layer 4) forming the n-side contact electrode. The p-type gallium nitride-based compound semiconductor layer and a part of the active layer excluding the region are etched down to the n-side contact layer 4. After etching, the etched surface is 300 ° C
The heat treatment is performed as described above. By this heat treatment, the ohmic property of the first layer made of W or Mo formed in the subsequent fourth step can be further improved. (Third Step) In the third step, a p-side layer made of a layer containing Ni and Au or a layer containing Ni and Pt is formed on almost the entire surface of the p-type gallium nitride-based compound semiconductor layer (the surface of the p-side contact layer 9). An ohmic electrode 10 is formed.

(Fourth Step) In the fourth step, the surface of the n-side contact layer 4 exposed in the second step and the surface of the p-side ohmic electrode 10 are formed on the first surface made of W or Mo, respectively.
Is formed. (Fifth Step) In a fifth step, a second layer made of Au or Pt is formed on the first layer. (Sixth step) In the sixth step, the first layer and the second layer formed in the fourth step and the fifth step are patterned into a predetermined shape to form the first layer 21 and the second layer. 22, an n-side contact electrode 20, a first layer 21a and a second
And the p-side pad electrode 11 made of the layer 22a.

(Seventh Step) In the seventh step, the p-side ohmic electrode 10, the p-side pad electrode 11 laminated thereon, and the n-side contact electrode 20 are heat-treated at a temperature of 500.degree. By this heat treatment, the p-side ohmic electrode 10
Can be brought into ohmic contact with the p-side contact layer 9. The first layer 21 of the n-side contact electrode 20
Reliability such as the heat resistance of the ohmic property can be improved. The reason why the reliability of the ohmic property of the first layer 21 of the n-side contact electrode 20 can be improved by the heat treatment will be described below. For example, when a protective film is formed by the CVD method after the formation of the n-side contact electrode 20, when soldering at the time of mounting, or when a large current flows during use of the semiconductor element, the n-side contact The temperature of the electrode 20 may be high and may be destroyed. However, the n-side contact electrode 20 is
If the heat treatment is performed at a relatively high temperature of ℃, the n-side contact electrode 20 will not be easily broken even at a high temperature. Therefore, reliability such as ohmic heat resistance of the first layer 21 of the n-side contact electrode 20 can be improved. The gallium nitride-based compound semiconductor device 30 of the first embodiment is manufactured by the manufacturing method described above.

In the nitride semiconductor device 30 of the first embodiment configured as described above, the n-side contact electrode 20
Is composed of a first layer 21 made of W or Mo and a second layer 22 made of Au or Pt.
Since the first layer 21 made of o makes good ohmic contact with the n-side contact layer 4, the following specific effects are further obtained. First, the n-side contact electrode 2
Since Al which limits the heat resistant temperature of the element to 0 is not used, the heat resistance of the semiconductor element 30 can be improved. Secondly, since the first layer and the second layer are formed using a high-melting-point material that is hardly oxidized and stable as described above, after these layers are laminated, the temperature of 500 ° C. or more is applied. Heat treatment can be performed at a relatively high temperature.
Thereby, reliability such as ohmic heat resistance between the n-side contact layer 4 and the n-side contact electrode 20 can be improved.

Further, in the first embodiment, the n-side contact electrode 20 and the p-side pad electrode 11 have a common structure including a first layer and a second layer, respectively, and the first layer has a high structure. Since the melting point material is formed using a stable metal which is hard to be oxidized as the second layer, after laminating these layers, heat treatment can be performed at a relatively high temperature of 500 ° C. or more. There are advantages such as: That is, in order for the p-side ohmic electrode 10 to make ohmic contact with the p-side contact layer 9, a heat treatment at a high temperature of about 500 ° C. is required. In the first embodiment, the n-side contact electrode 20 and the p-side pad are used. Since the first layer and the second layer of the electrode 11 are formed using a high-melting-point material which is hardly oxidized and stable, after laminating these layers, heat treatment is performed at a relatively high temperature of 500 ° C. or more. And a good ohmic contact can be made between the p-side ohmic electrode 10 and the p-side contact layer 9.

In the case where an n-side pad electrode is formed using Al as in the prior art, the heat treatment temperature is about 400.
C. or less, the heat treatment of the p-side contact electrode is performed at about 500 ° C. in the manufacturing process of the gallium nitride based compound semiconductor device, and then the heat treatment of the n-side contact electrode is performed at about 300 ° C. in another step. Had to be done in. On the other hand, according to the first embodiment, the p-side pad electrode 11
As described above, the n-side contact electrode 20 is hardly oxidized and is formed using a stable, high-melting-point material, and is not deteriorated by heat treatment at a high temperature of about 500 ° C. , P-side and n-side heat treatment can be performed at about 500 ° C. at one time, so that the manufacturing process can be simplified and the manufacturing cost can be reduced.

In the first embodiment, as a more preferable configuration, the p-side pad electrode 11 and the n-side contact electrode 20 are formed so as to have the same layer structure. It is not limited to. In the present invention, if at least the n-side contact electrode 20 is formed using the first and second layers as described above, p
The side pad electrode 11 may be formed using another layer.

(Embodiment 2) FIG. 2 is a schematic sectional view showing the structure of a gallium nitride based compound semiconductor device 32 according to another embodiment of the present invention. Hereinafter, with reference to FIG.
The gallium nitride-based compound semiconductor device 32 according to the second embodiment will be described. The same members as those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof will be omitted. In the gallium nitride-based compound semiconductor device 32 shown in FIG. 2, an n-side contact electrode 25 is formed instead of the n-side contact electrode 20 of the first embodiment, and a p-side contact is used instead of the p-side contact electrode 12. The configuration is the same as that of the first embodiment, except that the forming electrode 14 is formed.

More specifically, in the second embodiment, the n-side contact electrode 25 is composed of a first layer 21 made of W or Mo and a second layer made of Pt formed on the first layer 21. And a third layer 24 made of Au formed on the second layer 23. That is, the second embodiment includes two types of n-side contact electrodes 25 shown in Table 2 below.

[0034]

[Table 2]

Here, in the n-side contact electrode 25 of the second embodiment, the first layer 21 made of W or Mo is used.
Is a layer that makes ohmic contact with the n-side contact layer 4, and the thickness of the first layer 21 is 5n, as in the first embodiment.
It is preferable to set in the range of m to 100 nm. In the n-side contact electrode 25, a bonding wire is attached to the third layer 24 made of Au and connected to a desired external circuit. The second layer 23 and the third
Total film thickness with the layer 24 of about 300 nm or more and 10
It is preferably not more than μm. In the n-side contact electrode 25 of FIG. 2, since a bonding wire can be attached to the third layer 24, an n-side pad electrode is not separately provided. However, the present invention is not limited to this.
An n-side pad electrode may be separately provided on the side contact electrode 25.

As described above, in the nitride semiconductor device of Embodiment 2, the n-side contact electrode 25 is composed of the first layer 21 made of W or Mo and the Pt formed on the first layer 21. A second layer 23 made of Au, and a third layer 24 made of Au formed on the second layer 23, and n
A for limiting the heat resistant temperature of the element to the side contact electrode 25
Since l is not used, the same operation and effect as the nitride semiconductor device of the first embodiment are obtained.

In the second embodiment, the p-side contact electrode 14 formed on the p-side contact layer 10
Comprises a p-side ohmic electrode 10 and a p-side pad electrode 13. The p-side ohmic electrode 10 is a full-surface electrode formed on almost the entire surface of the p-side contact layer 9 similarly to the first embodiment, and is formed by a layer containing Ni and Au or a layer containing Ni and Pt. It makes ohmic contact with the p-side contact layer 9.

Further, in the second embodiment, the p-side pad electrode 13 formed on the p-side ohmic electrode 10
Has a configuration similar to that of the n-side contact electrode 25 described above, so that it can be manufactured in the same process as that of the n-side contact electrode 20, thereby simplifying the process. That is, the first layer 21b includes a first layer 21b, a second layer 23b formed on the first layer 21b, and a third layer 24b formed on the second layer 23b. Is made of W or Mo, the second layer 23b is made of Pt, and the third layer 24b is made of Au.

According to the second embodiment configured as described above, similarly to the first embodiment, the p-side pad electrode 13 is formed.
Each of the n-side contact electrodes 25 is formed using the above-listed high melting point materials of W or Mo and Pt or Au which are hardly oxidized and stable.
Even if heat treatment at a high temperature of about 500 ° C. is performed, there is no deterioration. Therefore, the p-side pad electrode 13 and the n-side contact electrode 25 can be heat-treated at about 500 ° C. at a time, thereby making ohmic contact on the p-side and ohmic contact resistance on the n-side. Therefore, the manufacturing process can be facilitated and the manufacturing cost can be reduced. Since the p-side pad electrode 13 and the n-side contact electrode 25 have the same layer structure, these electrodes 13 and 25 can be laminated in the same step. Therefore, the manufacturing process can be facilitated.

In the second embodiment, the p-side pad electrode 13 and the n-side contact electrode 25 are formed to have the same layer structure. However, the present invention is not limited to such a semiconductor device. Instead, if at least the n-side contact electrode 25 is formed using the first, second, and third layers as described above, the p-side pad electrode 11 may be formed using an arbitrary layer.

[0041]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described more specifically with reference to FIG. 1 using an embodiment, but the present invention is not limited thereto. (Substrate 1) Substrate 1 made of sapphire (C-plane)
The substrate is set in a PE reaction vessel, and while flowing hydrogen, the temperature of the substrate is raised to 1050 ° C. to clean the substrate. Another sapphire C face substrate 1, a sapphire having the principal R-plane, A plane, other, spinel (MgAl ₂
O ₄₎ other such insulating substrate, SiC (6H, 4
H, 3C), Si, ZnO, GaAs, GaN, and the like.

(First Buffer Layer 2) Subsequently, the temperature was set to 5
The temperature is lowered to 10 ° C., and a buffer layer 2 made of GaN is grown on the substrate 1 to a thickness of about 200 Å using hydrogen as a carrier gas and ammonia and TMG (trimethylgallium) as a source gas. The first buffer layer 2 grown at a low temperature can be omitted depending on the type of the substrate, the growth method, and the like.

(Second Buffer Layer 3) After growing the buffer layer 2, only TMG is stopped and the temperature is raised to 1050 ° C. When the temperature reaches 1050 ° C, TM
Using G and ammonia gas, a second buffer layer 3 made of undoped GaN is grown to a thickness of 1 μm. Second
Is grown at a higher temperature, for example, 900 ° C. to 1100 ° C., than the first buffer layer previously grown, and the In _x
It can be composed of Al _Y Ga _{1 -XYN} (0 ≦ X, 0 ≦ Y, X + Y ≦ 1), and its composition is not particularly limited.
When the aN and X value are Al _x Ga ₁ -xN of 0.2 or less, a nitride semiconductor layer with few crystal defects is easily obtained. The thickness is not particularly limited, and the film is grown with a thickness larger than that of the buffer layer, and usually with a thickness of 0.1 μm or more.

(N-side contact layer 4) Subsequently, at 1050 ° C.
Then, an n-side contact layer made of GaN doped with 3 × 10 ¹⁹ / cm ^{3 of} Si is grown to a thickness of 3 μm using TMG, ammonia gas and silane gas as source gases. Similarly to the second buffer layer 3, the n-side contact layer 4 is made of In _x Al _Y Ga _{1 -XYN} (0 ≦ X, 0 ≦
Y, X + Y ≦ 1), and the composition thereof is not particularly limited, but is preferably GaN, Al _X having an X value of 0.2 or less.
When Ga ₁ -xN is used, a nitride semiconductor layer with few crystal defects is easily obtained. There is no particular limitation on the film thickness, but since it is a layer for forming an n-electrode, it is desirable to grow the film to a thickness of 1 μm or more. Further, the n-type impurity concentration is desirably doped at a high concentration so as not to deteriorate the crystallinity of the nitride semiconductor, and is preferably doped within a range of 1 × 10 ¹⁸ / cm ³ or more and 5 × 10 ²¹ / cm ³ or less. desirable.

(Third Buffer Layer 5) Next, only the silane gas is stopped, and a third buffer layer 5 made of undoped GaN is grown in the same manner at 1050 ° C. to a thickness of 100 Å. This third buffer layer 5 is also made of In _X A
1 _Y Ga _{1 -XYN} (0 ≦ X, 0 ≦ Y, X + Y ≦ 1), and the composition is not particularly limited, but is preferably G
When aN and Al _x Ga ₁ -xN having an X value of 0.2 or less or In _Y Ga ₁ -yN having a y value of 0.1 or less, a nitride semiconductor layer having few crystal defects can be easily obtained. This undoped GaN
Unlike the case where the active layer is grown directly on the n-side contact layer 4 doped with the impurity at a high concentration by growing the layer, the crystallinity of the base is improved, so that the nitride semiconductor to be grown next is grown. Easy to do. As described above, on the second buffer layer 3 made of the undoped nitride semiconductor layer, the n-side contact layer 4 made of the nitride semiconductor doped with the n-type impurity at a high concentration, and then the undoped nitride semiconductor ( If a three-layer structure is used in which the third buffer layer 5 made up of an n-side multilayer film layer is included, Vf tends to decrease when an LED element is used. When the n-side multilayer film layer 6 is undoped, the third buffer layer 5 can be omitted.

(N-side multilayer film layer (photoluminescence layer)
6) Next, at a similar temperature, a second nitride semiconductor layer made of undoped GaN is grown at 40 °, and then the temperature is increased to 80 °.
In the 0 ℃, TMG, TMI, SiH 4, with ammonia, to supply 1.25nmol the Si, the first nitride semiconductor layer made of In _{0. 3} Ga _{0. 7} N doped with Si 20
さ せ る Grow. And these operations are repeated, and the second +
An n-side second multilayer film layer 6 composed of a superlattice-structure multilayer film in which 30 layers are alternately stacked in the first order and finally a second nitride semiconductor layer made of GaN is grown by 40 ° is a 1840 ° film. Grow in thickness.

(Active Layer 7) Next, a barrier layer made of undoped GaN is grown to a thickness of 200 angstroms, then the temperature is set to 800 ° C., and undoped In _0.3 Ga _0.7 N using TMG, TMI and ammonia. A well layer having a thickness of 30 Å is grown. Then, five barrier layers and four well layers are alternately stacked in the order of barrier + well + barrier + well... + Barrier to grow an active layer 7 having a multiple quantum well structure having a total thickness of 1120 Å. Let it. Although the active layer 7 is stacked from the barrier layer, the stacking order may be the stacking from the well layer and ending with the well layer. The order of lamination is not particularly limited.
The thickness of the well layer is adjusted to 100 angstroms or less, preferably 70 angstroms or less, and more preferably 50 angstroms or less. If the thickness is more than 100 Å, the output tends to be hardly improved. On the other hand, the thickness of the barrier layer is adjusted to 300 angstrom or less, preferably 250 angstrom or less, and most preferably 200 angstrom or less.

(P-side multilayer film layer 8) Next, TMG, TM
A, ammonia, Cp ₂ Mg (cyclopentadienyl magnesium), a third nitride semiconductor layer of p-type Al _0.05 Ga _0.95 N doped with Mg at 5 × 10 ¹⁹ / cm ³ having a thickness of 25 Å And then C
Stopping p ₂ Mg, TMA, 4th of undoped GaN
Is grown to a thickness of 25 Å. Then, these operations are repeated to grow a p-side multilayer film layer 8 of a superlattice having a thickness of 200 angstroms, which is formed by superimposing four layers alternately in the third + fourth order.

(P-side contact layer 9) Subsequently, at 1050 ° C.
And using TMG, ammonia and Cp ₂ Mg,
A p-side contact layer 8 made of p-type GaN doped with × 10 ²⁰ / cm ³ is grown to a thickness of 700 Å. The p-side contact layer 8 is also formed of In _x Al _Y Ga _{1 -XYN} (0
.Ltoreq.X, 0.ltoreq.Y, X + Y.ltoreq.1), and the composition thereof is not particularly limited. However, when GaN is used, a nitride semiconductor layer with few crystal defects can be easily obtained. Contact is easy to obtain. After completion of the reaction, the temperature is lowered to room temperature, and the wafer is annealed at 700 ° C. in a reaction vessel in a nitrogen atmosphere to further reduce the resistance of the p-type layer.

(P-side contact electrode 12 and n-side contact electrode 20) After annealing, the wafer is taken out of the reaction vessel, a mask having a predetermined shape is formed on the surface of the uppermost p-side contact layer 9, and RIE ( The surface of the n-side contact layer 4 is exposed as shown in FIG. After the exposure, the surface of the n-side contact layer 4 is
Heat treatment at 0 ° C. or higher. Subsequently, Ni and Au with a film thickness of 20 nm are formed on the entire surface from the side of the surface of the p-side contact layer by using an evaporation apparatus such as sputtering, and the Ni and Au on the n-side contact layer are removed by wet etching. Thus, the translucent p-side ohmic electrode 10
Was formed. Next, on the p-side ohmic electrode 10 and n
A portion of the entire surface on the side contact layer 4 where the p-side pad electrode and the n-side contact electrode are not formed is masked, and the entire surface from the surface of the p-side contact layer is made of W using a sputtering apparatus. A first layer is formed with a thickness of 200 Å and a second layer of Pt is formed with a thickness of 6000 Å. Finally, the photoresist is removed, an n-side contact electrode 20 including a first layer 21 and a second layer 22 is formed on the n-side contact layer 4, and the first electrode 20 is formed on the p-side ohmic electrode 10. The p-side pad electrode 11 composed of the layer 21 and the second layer 22 was formed. Finally nitride semiconductor exposed surface of the entire surface protective film, as an antistatic film was formed an SiO ₂ with a thickness of 200 nm.
At this time, if about 100 Å of Ni is formed between SiO ₂ and the n-side contact electrode and the p-side pad electrode, the adhesion of SiO ₂ is improved. Finally S
A part of iO ₂ (and Ni) was etched to expose a part of the n-side ohmic electrode and a part of the p-side pad electrode. As described above, an LED element was manufactured.

[0051]

As described above, according to the present invention, good ohmic contact with the n-type gallium nitride-based compound semiconductor layer can be obtained, and the n-side contact electrode which does not deteriorate even by heat treatment at about 500 ° C. And a method for manufacturing the same.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view illustrating a structure of a gallium nitride-based compound semiconductor device according to a first embodiment of the present invention.

FIG. 2 is a schematic cross-sectional view illustrating a structure of a gallium nitride-based compound semiconductor device according to a second embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 2 1st buffer layer 3 2nd buffer layer 4 n side contact layer 5 3rd buffer layer 6 n side multilayer film layer 7 active layer 8 p side multilayer film layer 9 p side contact layer 10 p side ohmic electrode Reference Signs List 11 p-side pad electrode 12 p-side contact electrode 13 p-side pad electrode 14 p-side contact electrode 20 n-side contact electrode 21 first layer 21 a first layer 21 b first layer 22 second layer 22 a 2nd layer 23 2nd layer 23b 2nd layer 24 3rd layer 24b 3rd layer 30 gallium nitride based compound semiconductor device 32 gallium nitride based compound semiconductor device

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[Procedure amendment]

[Submission Date] May 30, 2001 (2001.5.3)
0)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0004

[Correction method] Change

[Correction contents]

[0004]

In order to solve the above-mentioned problems of the prior art, a first gallium nitride-based compound semiconductor device according to the present invention comprises an n-type gallium nitride-based compound semiconductor layer and the n-type gallium nitride-based compound semiconductor layer. In a gallium nitride-based compound semiconductor device having an n-side contact electrode in ohmic contact with a gallium nitride-based compound semiconductor layer, the n-side contact electrode is made of a first layer made of W or Mo, and the first layer And a second layer made of Pt formed thereon, wherein the first layer is in ohmic contact with the n-type gallium nitride-based compound semiconductor layer.

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0005

[Correction method] Change

[Correction contents]

In the gallium nitride-based compound semiconductor device of the present invention thus configured, the n-side contact electrode is
Since it is configured to include the first layer made of W or Mo and the second layer made of Pt thereon, the first layer of the n-side contact electrode and the n-type gallium nitride-based compound semiconductor layer Even if the heat treatment is performed at a relatively high temperature in order to improve the reliability such as the heat resistance of the ohmic property, the electrode for the n-side contact hardly deteriorates. Further, an n-side contact electrode is formed of a first layer made of W or Mo and a P layer thereon.
Since the semiconductor device is formed using the second layer made of t, it can be formed without containing Al, and the gallium nitride-based compound semiconductor device of the present invention can be compared with the conventional example including the Al layer. Then, heat resistance can be improved.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0010

[Correction method] Change

[Correction contents]

[0010] A third gallium nitride-based compound semiconductor device according to the present invention comprises: an n-type gallium nitride-based compound semiconductor layer;
An n-side contact electrode formed on a part of the upper surface of the n-type gallium nitride-based compound semiconductor layer; and an n-side contact electrode formed on the upper surface of the n-type gallium nitride-based compound semiconductor layer so as to be separated therefrom. Active layer, a p-type gallium nitride-based compound semiconductor layer formed on the active layer, and a p-type gallium nitride-based compound semiconductor layer formed on the p-type gallium nitride-based compound semiconductor layer.
A gallium nitride-based compound semiconductor device comprising: a p-side ohmic electrode; a p-side pad electrode formed on the p-side ohmic electrode; The side contact electrode and the p-side pad electrode are the same as each other,
It is characterized by comprising a first layer made of W or Mo, and a second layer made of Pt formed on the first layer.

[Procedure amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0014

[Correction method] Change

[Correction contents]

In a first method of manufacturing a gallium nitride compound semiconductor device according to the present invention, an n-type gallium nitride compound semiconductor layer, an active layer, and a p-type gallium nitride compound semiconductor layer are formed on a substrate. Sequentially growing a p-type gallium nitride-based compound semiconductor layer, and etching a part of the p-type gallium nitride-based compound semiconductor layer and the active layer to expose a part of the n-type gallium nitride-based compound semiconductor layer Forming a p-side ohmic electrode on the surface of the p-type gallium nitride-based compound semiconductor layer;
W is formed on the exposed n-type gallium nitride-based compound semiconductor layer and on the p-side ohmic electrode, respectively.
Alternatively, a step of stacking a first layer made of Mo, a step of stacking a second layer made of Pt on the first layer, the step of stacking the p-side ohmic electrode, the step of forming the first and second layers, Heat treating the layer at 500 ° C. or higher.

[Procedure amendment 6]

[Document name to be amended] Statement

[Correction target item name] 0015

[Correction method] Change

[Correction contents]

In the above first manufacturing method, the first layer made of W or Mo and the second layer made of Pt thereon are formed as the n-side contact electrode. Heat treatment can be performed at a relatively high temperature of 500 ° C. or more, and reliability such as ohmic heat resistance of the first layer made of W or Mo with respect to the n-type gallium nitride-based compound semiconductor layer can be improved. . In addition, since the n-side contact electrode is formed using the first layer made of W or Mo and the second layer made of Pt thereon, it can be formed without containing Al. A gallium nitride-based compound semiconductor device having higher heat resistance than that of the conventional example including the Al layer can be manufactured. Further, in the above-described first manufacturing method, the n-side contact electrode and the p-side pad electrode can be manufactured by a common process using the first layer and the second layer, thereby simplifying the manufacturing process. can do.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01L 29/43 H01L 29/46 H (72) Inventor Tatsunori Toyoda 491 Kaminakachooka, Anan-shi, Tokushima 100 100 days F term (reference) in Aka Chemical Industry Co., Ltd. 4M104 AA01 AA04 AA10 BB05 BB06 BB07 BB09 BB16 BB18 CC01 DD37 DD64 DD68 DD78 FF03 FF13 GG04 HH15 HH20 5F041 CA40 CA82 CA85 CA92

Claims (11)

[Claims] An n-type gallium nitride-based compound semiconductor layer;
A gallium nitride-based compound semiconductor device having an n-side contact electrode in ohmic contact with the n-type gallium nitride-based compound semiconductor layer, wherein the n-side contact electrode is a first layer made of W or Mo; Au or P formed on the first layer
a gallium nitride-based compound semiconductor device, comprising a second layer made of t, wherein the first layer and the n-type gallium nitride-based compound semiconductor layer are in ohmic contact with each other. 2. The gallium nitride based compound semiconductor device according to claim 1, wherein said first layer has a thickness of about 100 nm or less, and said second layer has a thickness of about 300 nm or more. 3. An n-type gallium nitride-based compound semiconductor layer,
A gallium nitride-based compound semiconductor device having a contact electrode in ohmic contact with the n-type gallium nitride-based compound semiconductor layer, wherein the n-side contact electrode includes a first layer made of W or Mo; A second layer made of Pt formed on the first layer, and a third layer made of Au formed on the second layer, wherein the first layer and the n-type nitride are formed. A gallium nitride-based compound semiconductor element in which an ohmic contact is made with a gallium-based compound semiconductor layer. 4. The nitride according to claim 3, wherein the thickness of the first layer is about 100 nm or less, and the total thickness of the second layer and the third layer is about 300 nm or more. Gallium compound semiconductor device. 5. An n-type gallium nitride-based compound semiconductor layer,
An n-side contact electrode formed on a part of the upper surface of the n-type gallium nitride-based compound semiconductor layer; and an n-side contact electrode formed on the upper surface of the n-type gallium nitride-based compound semiconductor layer so as to be separated therefrom. Active layer, a p-type gallium nitride-based compound semiconductor layer formed on the active layer, and a p-type gallium nitride-based compound semiconductor layer formed on the p-type gallium nitride-based compound semiconductor layer.
A gallium nitride-based compound semiconductor device provided with a side contact electrode, wherein the p side contact electrode includes a p side ohmic electrode and a p side pad electrode formed on the p side ohmic electrode; The side contact electrode and the p-side pad electrode are identical to each other, and each includes a first layer made of W or Mo, and a second layer made of Au or Pt formed on the first layer. A gallium nitride-based compound semiconductor device comprising: 6. An n-type gallium nitride-based compound semiconductor layer,
An n-side contact electrode formed on a part of the upper surface of the n-type gallium nitride-based compound semiconductor layer; and an n-side contact electrode formed on the upper surface of the n-type gallium nitride-based compound semiconductor layer so as to be separated therefrom. Active layer, a p-type gallium nitride-based compound semiconductor layer formed on the active layer, and a p-type gallium nitride-based compound semiconductor layer formed on the p-type gallium nitride-based compound semiconductor layer.
A gallium nitride-based compound semiconductor device provided with a side contact electrode, wherein the p side contact electrode includes a p side ohmic electrode and a p side pad electrode formed on the p side ohmic electrode; The side contact electrode and the p-side pad electrode are the same as each other, and a first layer made of W or Mo and a second layer made of Pt formed on the first layer, respectively.
And a third layer made of Au formed on the second layer.
A gallium nitride-based compound semiconductor device comprising: 7. The p-side ohmic electrode includes Au, P
The gallium nitride-based compound semiconductor device according to claim 5, wherein the gallium nitride-based compound semiconductor device is formed of a metal or an alloy containing at least one of t, Ni, and Pd. 8. The gallium nitride-based compound semiconductor device according to claim 7, wherein said p-side ohmic electrode is formed of an alloy comprising Ni and Au. 9. The gallium nitride-based compound semiconductor device according to claim 7, wherein said p-side ohmic electrode is formed of an alloy comprising Ni and Pt. 10. A step of sequentially growing an n-type gallium nitride-based compound semiconductor layer, an active layer, and a p-type gallium nitride-based compound semiconductor layer, each comprising a gallium nitride-based compound semiconductor, on the substrate; Etching a part of the gallium-based compound semiconductor layer and the active layer to expose a part of the n-type gallium nitride-based compound semiconductor layer; Forming an ohmic electrode; and forming W on the exposed n-type gallium nitride-based compound semiconductor layer and on the p-side ohmic electrode, respectively.
Or a step of laminating a first layer made of Mo; a step of laminating a second layer made of Au or Pt on the first layer; the p-side ohmic electrode; Heat treating the second layer at 500 ° C. or higher. 11. A step of sequentially growing an n-type gallium nitride-based compound semiconductor layer, an active layer, and a p-type gallium nitride-based compound semiconductor layer each comprising a gallium nitride-based compound semiconductor on a substrate; Etching a part of the gallium-based compound semiconductor layer and the active layer to expose a part of the n-type gallium nitride-based compound semiconductor layer; Forming an ohmic electrode; and forming W on the exposed n-type gallium nitride-based compound semiconductor layer and on the p-side ohmic electrode, respectively.
Or a step of laminating a first layer of Mo; a step of laminating a second layer of Pt on the first layer; and a third layer of Au on the second layer. And a step of heat-treating the p-side ohmic electrode and the first, second, and third layers at 500 ° C. or higher.