JP2003124124A - Semiconductor element, epitaxial substrate, method of manufacturing semiconductor element, and method of manufacturing epitaxial substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor element that is improved in crystal quality by the reducing dislocation density and to provide an epitaxial substrate used for the element. SOLUTION: On a base material 11 composed of a single-crystal material, a foundation layer 12 composed of an Al-containing III nitride is formed. Then a mask 14 is formed on the foundation layer 12 in a pattern-like form and an initial epitaxially-grown layer 16 having facets 15 and composed of a III nitride is formed through the mask 14. Thereafter, an intermediate layer 13 having the facets 15 is formed by again epitaxially growing the III nitride so that the nitride may bury the initial epitaxially grown layer 16 and may have a flat surface.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device, an epitaxial substrate, a method for manufacturing a semiconductor device, and a method for manufacturing an epitaxial substrate, and more specifically, semiconductor devices such as photonic devices and electronic devices, and field emitters. The present invention relates to a semiconductor element that can be preferably used as an element, an epitaxial substrate that can be preferably used as a substrate that constitutes the element, and a manufacturing method thereof.

[0002]

2. Description of the Related Art Group III nitride films are used as semiconductor films for forming semiconductor elements such as photonic devices and electronic devices, and in recent years, they have become high-speed IC chips for mobile phones. It is also drawing attention as a semiconductor film. In addition, especially containing Al III
Group nitride films have attracted attention as a material applied to field emitters.

In recent years, such III
A so-called epitaxial substrate having a base film formed by epitaxial growth on a predetermined base material is frequently used as a substrate for forming a group nitride film. Then, a predetermined semiconductor element layer formed by laminating a single-layer III-nitride film or a plurality of III-nitride films is formed on this epitaxial substrate by using the MOCVD method or the like to obtain a target element. Is getting

It is preferable that the underlayer film is made of a group III nitride containing Al so as to facilitate the epitaxial growth of the group III nitride film containing Al. Further, since the Al-containing nitride has a large band gap, by inserting an underlayer film made of such a material having a large band gap between the group III nitride film and the base material, the efficiency of a semiconductor device or the like can be improved. It can also be improved.

However, in the element thus manufactured, the base material that constitutes the epitaxial substrate and A
Misfit dislocations are generated due to the difference in lattice constant from the l-containing group III nitride underlayer, and these misfit dislocations penetrate through the Al-containing group III nitride underlayer as threading dislocations, That is, it reaches the surface of the epitaxial substrate. Therefore, a large amount of dislocations due to the misfit dislocations are generated also in the semiconductor element layer formed on the Al-containing group III nitride underlayer film, that is, on the epitaxial substrate.

From such a viewpoint, the EL is formed on the underlayer.
Attempts have been made to form an intermediate layer by the O technique, or to form the underlayer itself by the ELO technique.

1 and 2 are cross-sectional views showing a manufacturing process in the case of forming an intermediate layer on an underlayer by using the ELO technique. As shown in FIG. 1, a base layer 1 made of, for example, Al-containing group III nitride is formed by epitaxial growth on a substrate 1 made of a single crystal material, and then a mask 4 made of SiO ₂ or the like is formed in a pattern. . After that, Figure 2
As shown in, through the mask 4 on the underlayer 2, for example,
The intermediate layer 3 made of a group III nitride is epitaxially grown.

At this time, dislocations generated at the interface between the base material 1 and the underlayer 2 propagate through the intermediate layer 3 after penetrating the underlayer 2. When the intermediate layer 4 grows in the lateral direction toward the mask 4 in the process of manufacturing the intermediate layer 3, some of the dislocations are bent in the lateral direction as indicated by a region B in the drawing. As a result, the dislocations penetrating through the intermediate layer 3 are limited to those shown in the region A in the figure, and the proportion of threading dislocations in the intermediate layer 3 is reduced.

[0009]

However, even in this case, since a considerable amount of threading dislocations are present in the intermediate layer 3, the intermediate layer 3 functions as a semiconductor element on the intermediate layer 3.
When a semiconductor element layer having a single layer or a multilayer structure is formed,
There is a problem that the dislocation density in the semiconductor element layer cannot be reduced sufficiently. This tendency becomes remarkable as the underlayer 2 is composed of a group III nitride containing Al and the Al content increases.

Therefore, for example, when a semiconductor light emitting device or the like is manufactured as described above, the light emitting efficiency is deteriorated, and it is not possible to obtain a semiconductor light emitting device having desired characteristics.

It is an object of the present invention to provide a semiconductor device having a reduced dislocation density and excellent crystal quality, and an epitaxial substrate used for the same. Further, it is an object of the present invention to provide a method for manufacturing the semiconductor device and the epitaxial substrate.

[0012]

[Means for Solving the Problems] In order to achieve the above object,
The present invention provides a base material made of a single crystal material, an underlayer made of an Al-containing first group III nitride formed adjacent to the base material, and a base layer formed adjacent to the base layer. III of 2
An intermediate layer made of a group nitride, and a semiconductor element layer made of a third group III nitride formed adjacent to the intermediate layer, the intermediate layer being inclined at a constant angle from the underlayer. Characterized by having raised facets,
Regarding semiconductor devices.

The present invention also provides a base made of a single crystal material and an Al-containing first II formed adjacent to the base.
An underlayer made of a group I nitride and an intermediate layer made of a second group III nitride formed adjacent to the underlayer,
The intermediate layer according to the present invention relates to an epitaxial substrate, characterized in that it has facets inclined and rising from the underlayer at a constant angle.

As a result of earnest studies to achieve the above object, the inventors of the present invention have formed an intermediate layer having facets which are inclined and rise from the underlayer at a constant angle on the underlayer to form the intermediate layer. We have found that we can achieve the purpose.

FIG. 3 is a sectional view showing an example of the epitaxial substrate of the present invention. In the epitaxial substrate 10 shown in FIG. 3, an underlayer 12 made of an Al-containing group III nitride and an intermediate layer 13 made of a group III nitride are sequentially formed on a base material 11 made of a predetermined single crystal material. . The intermediate layer 13 has a facet 15 that is inclined and rises at a constant angle from the underlayer 12 around a mask 14 formed in a pattern on the underlayer 12.

Dislocations generated at the interface between the base material 11 and the underlayer 12 propagate through the intermediate layer 13 after penetrating the underlayer 12, and most of them are facets 15 as shown by arrows in the figure. And can be bent laterally. Therefore, the number of dislocations propagating over the facets 15 is significantly reduced, and the dislocation density above the intermediate layer 13 is significantly reduced. As a result, when a semiconductor element layer made of a group III nitride is formed on the intermediate layer 13, the dislocation density in this element layer is also significantly reduced and the crystal quality is improved. Therefore,
It becomes possible to provide an epitaxial substrate and a semiconductor device having excellent crystal quality.

As a result, when a semiconductor light emitting device or the like is constructed from the semiconductor device of the present invention, the luminous efficiency is improved due to the high crystal quality and the fact that the underlayer is made of an Al-containing group III nitride. Significantly improved.

The preferred embodiments of the semiconductor device and the epitaxial substrate of the present invention, the method of manufacturing the semiconductor device of the present invention, and the method of manufacturing the epitaxial substrate will be described in detail below in the embodiments of the invention.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below in detail based on embodiments of the invention with reference to the drawings.

4 and 5 are sectional views for explaining an example of the method for manufacturing an epitaxial substrate of the present invention.
First, as in the conventional ELO technique shown in FIG. 1, as shown in FIG.
The underlayer 12 made of l-containing group III nitride is formed by epitaxial growth. Next, a mask 14 is formed in a pattern on the underlayer 12 by a vapor deposition method or the like. The width of the mask 14 is set to, for example, 0.1 μm to 50 μm,
An adjacent mask interval (opening width) P is, for example, 0.1 μm.
˜50 μm, more preferably 1 μm to 10 μm.

Next, as shown in FIG. 5, the group III nitride forming the intermediate layer 13 is epitaxially grown on the underlayer 12 with the mask 14 interposed therebetween, and the III-nitride is formed from the underlayer 12 with the mask 14 at the center. An initial epitaxial growth layer 16 having a facet 15 which is inclined and rises at an angle of is formed (first epitaxial growth). Next, the epitaxial conditions are changed, the initial epitaxial growth layer 16 is buried, and the group III nitride is epitaxially grown so as to be planarized (second epitaxial growth), and the intermediate layer 13 as shown in FIG. 3 is formed.

The first epitaxial growth and the second epitaxial growth are performed by appropriately selecting temperature and pressure. For example, the first epitaxial growth is performed under the conditions of low temperature or low pressure with respect to the second epitaxial growth. Specifically, the first
Epitaxial growth at 950 ° C. and 200 Torr, and second epitaxial growth at 1070 ° C. and 5 Torr
Perform at 00 Torr.

The mask 14 is preferably formed so that its longitudinal direction is parallel to the <10-10> direction of the group III nitride constituting the underlayer. by this,
The initial epitaxial growth layer 16 is easily formed along the <0001> direction of the group III nitride forming the underlayer 12, and has the facets 15 inclined in the direction. That is, it is possible to easily form the initial epitaxial growth layer 16 having the facets 15 that are inclined and rise from the underlayer 12 at a constant angle.

The mask 14 is made of SiO ₂ , SiOx, Si.
It can be formed by using Nx or other refractory metal material.

The underlayer 12 needs to be composed of a group III nitride containing Al, and when forming a practical epitaxial substrate, that is, a semiconductor device, Alx1Gay1Inz1N (x1 + y1 + z1 =
1, x1 ≧ 0.5, y1 ≧ 0, z1 ≧ 0), and more preferably AlN.

Further, the intermediate layer 13 needs to be composed of a group III nitride, and when forming a practical epitaxial substrate, that is, a semiconductor element, Alx is used.
2Gay2Inz2N (x2 + y2 + z2 = 1, x2 ≧
It is preferable to have a composition of 0, y2 ≧ 0, z2 ≧ 0). Then, in this case, x1 and x2 that define the Al composition ratio between the group III nitride forming the underlayer 12 and the group III nitride forming the intermediate layer 13 are:
It is preferable that the relationship x2 ≦ x1-0.1 is satisfied.

As described above, since the underlayer 12 and the intermediate layer 13 have a difference in Al composition concentration of 10 atomic% or more at the interface, the threading dislocation propagated in the underlayer 12 has the difference in Al composition concentration. It becomes difficult to propagate beyond the interface having the. Therefore, the dislocation density in the intermediate layer 13 can be further reduced.

The base layer 12 and the intermediate layer 13 may be made of Ge, Si, Mg, Ca, Zn, Be, P, A, if necessary.
Elements such as s and B may also be contained. further,
Not only the elements that are intentionally added, but also impurities that are necessarily included depending on the film forming conditions and the like, and trace impurities that are included in the raw materials and the material of the reaction tube are included.

Further, the underlayer 12 is made of the X of the (0002) plane.
It is preferably composed of a highly crystalline Al-containing group III nitride having a line rocking curve full width at half maximum of 100 seconds or less.
As a result, the intermediate layer 13 formed on the underlayer 12,
In addition, the crystallinity of the predetermined semiconductor element layer can be improved, and the crystallinity of the epitaxial substrate 10 shown in FIG. 3 and the entire semiconductor element including the epitaxial substrate 10 and the predetermined semiconductor element layer can be improved. Therefore, the device characteristics can be dramatically improved.

For the same reason, the main surface 12A of the underlayer 12 is
Preferably has a high surface flatness with a surface average roughness Ra of 2Å or less.

Such an underlayer 12 is, for example, MOC.
It can be formed by using the VD method and heating the substrate 11 to 1100 ° C. or higher, preferably 1250 ° C. or lower. Conventionally, the base layer has functioned as a buffer layer for compensating for the difference in lattice constant between the base material and the semiconductor element layer. Therefore, the base material is heated to 500 to 600 ° C., and low crystalline GaN or AlN is used. It consisted of However, Group III nitrides containing a relatively large amount of Al, especially Al
The present inventors have found that when the underlayer is composed of N, even if the crystallinity is improved by high temperature film formation, the difference in lattice constant as described above can be sufficiently complemented.

Further, even when the lattice constant difference is not sufficiently complemented and a relatively large amount of misfit dislocations are generated, the dislocation density in the intermediate layer can be sufficiently reduced by the facet effect described above. Further, the underlayer and the intermediate layer have Al of 10 atomic% or more as described above.
Due to the difference in composition concentration, the dislocation density in the intermediate layer is sufficiently reduced.

The substrate 11 is made of sapphire single crystal, ZnO single crystal, LiAlO ₂ single crystal, LiGaO ₂ single crystal, Mg.
Al ₂ O ₄ single crystals, oxide single crystals such as MgO single crystals,
Group IV or IV-IV group single crystals such as Si single crystal and SiC single crystal, GaAs single crystal, AlN single crystal, III-V group single crystal such as GaN single crystal and AlGaN single crystal, ZrB
It can be composed of a known substrate material such as a boride single crystal such as ₂ .

In particular, when the base material 11 is made of sapphire single crystal, it is preferable that the main surface 11A of the base material 11 is subjected to surface nitriding treatment to form a surface nitrided layer. As a result, the underlayer 12, and further the intermediate layer 1
3 and the crystallinity of the semiconductor element layer to be formed on the intermediate layer 13 can be further improved.

By the ESCA analysis, the surface nitrided layer has a nitrogen content of 2 at a depth of 1 nm from the main surface 11A.
It is formed to have a thickness of not less than atomic% and not more than 50 atomic%. The surface nitrided layer having such a thickness is formed by placing the base material 11 in an atmosphere containing nitrogen such as ammonia and heating it for a predetermined time. And
It is formed by appropriately controlling the nitrogen concentration, nitriding temperature, and nitriding time.

In obtaining the semiconductor device of the present invention, a semiconductor device layer made of a predetermined group III nitride is formed on the epitaxial substrate manufactured as described above, that is, on the intermediate layer. This semiconductor element layer can have a single layer or a multilayer structure depending on the purpose. Since the dislocation density of the surface layer portion of the intermediate layer located at the top of the epitaxial substrate is sufficiently reduced by the facets, the dislocation density in the semiconductor element layer is 10 ⁵ -10 ⁷ / cm ^2.
It is reduced to the extent.

The semiconductor element layer can be manufactured in the same batch as the epitaxial substrate, or in different batches. The semiconductor element layer can be manufactured using the same device as the epitaxial substrate, or can be manufactured using a different device. Furthermore, only the intermediate layer that constitutes the epitaxial substrate can be manufactured by using different batches or different devices.

[0038]

EXAMPLES The present invention will be specifically described below with reference to examples. (Example)

A C-plane sapphire single crystal was used as the substrate 11, and this was placed on a susceptor installed in a quartz reaction tube. Then set the pressure to 15 Torr,
After supplying the hydrogen carrier gas at a flow rate of 3 m / sec, the substrate 11 was heated to 1200 ° C. by the heater.

Next, ammonia gas (NH ₃ ) was flown with the hydrogen carrier gas for 5 minutes to nitride the main surface of the base material 11. As a result of analysis by ESCA, it was found that a nitride layer was formed on the main surface by this surface nitriding treatment, and the nitrogen content at a depth of 1 nm from the main surface was 7 atom%.

Next, trimethylaluminum (TMA) was used as the Al feedstock, and ammonia gas (NH ₃ ) was used as the nitrogen feedstock, and these feedstock gases were used together with the hydrogen carrier gas so that the molar ratio of TMA and NH ₃ was 1. : 450, and was supplied onto the base material 11. And 120
By epitaxial growth for a minute, an AlN film as a base layer was formed to a thickness of 2 μm.

When the surface flatness of this AlN base film was evaluated, it was found that the film had a flatness of 2Å with Ra of 5 μm square, and the rocking curve half width of (0002) was 50.
It was found to exhibit high crystals of seconds.

Then, a film forming process is performed on the AlN film through a predetermined mask to form a SiO ₂ mask having a mask width of 5 μm and an opening width of 5 μm, the longitudinal direction of which is A.
It was formed so as to be parallel to the <10-10> direction of the 1N film.

Next, the pressure was changed to 200 Torr, the substrate temperature was changed to 950 ° C., trimethylgallium (TMG) was used as a Ga feedstock, and the flow rate ratio of the feedstock gas was set to (T
MG + TMA) and NH ₃ were supplied at a molar ratio of 1: 1500 onto the AlN film and epitaxially grown for 45 minutes to form an initial epitaxial growth layer having a {11-22} facet. . After that, the pressure is 500 Torr and the substrate temperature is 10
The temperature was changed to 70 ° C. and Al _0.05 Ga as an intermediate layer was used.
_{A 0.95} N layer was formed to a thickness of 10 μm to complete an epitaxial substrate.

Thereafter, SiH ₄ gas was added under the same conditions,
N-type Al _0.05 Ga constituting the bottom layer of the semiconductor element layer
_{A 0.95} N layer was formed to a thickness of 3 μm to complete a semiconductor device. When the dislocation density in this Al _0.05 Ga _0.95 N layer was examined by TEM observation, it was 5 × 10 ⁶ / c.
It was found to be m ² .

(Comparative Example) Pressure is 500 Torr, substrate temperature
The temperature is set to 1070 ° C and (TMG + TM
A) and NH_ThreeSet so that the molar ratio with
As the intermediate layer that constitutes the epitaxial substrate.
Al without set_0.05Ga_{0.9 5}N layer thickness
A semiconductor was manufactured in the same manner as in the example except that the thickness was 10 μm.
A device was produced. Semiconductor formed on an epitaxial substrate
Al as body element layer_0.05Ga _0.95Transfer in N layer
When the density is examined by TEM observation, it is 5 × 10⁷
/ Cm^TwoIt turned out to be

As is clear from the above examples and comparative examples, an epitaxial substrate was prepared by using the conventional ELO technique shown in the comparative example, and Al _0.05 Ga _{0. 95}
Compared with the case where the N semiconductor element layer is formed, Al _0.05 Ga _0.95 formed on the epitaxial substrate of the present invention
It can be seen that the N semiconductor element layer has the dislocation density improved by one digit and the crystal quality is greatly improved.

The present invention has been described in detail based on the embodiments of the invention with reference to specific examples, but the invention is not limited to the embodiments of the invention described above, and the scope of the invention is not limited thereto. All changes and modifications are possible without departing from the scope.

For example, although the case where the underlayer 12 and the intermediate layer 13 are single layers has been described above,
These may have a multi-layer structure. Further, the composition can be changed in the thickness direction. In this case, the composition and the crystallinity mean those over the entire underlayer and intermediate layer.

Further, a multilayer laminated film such as a buffer layer or a strained superlattice is inserted between the base material and the underlayer, or between the underlayer and the intermediate layer, and the crystallinity of the underlayer or the intermediate layer is increased. Further, it is possible to provide an epitaxial substrate having excellent crystallinity and a semiconductor element. Further, for example, the conductivity of the underlayer may be controlled so that the underlying substrate has the function of the semiconductor element layer. Furthermore, using a HVPE method on the underlying substrate, a thick film III
The semiconductor element layer may be formed after the group nitride film is once grown.

[0051]

As described above, according to the present invention,
It is possible to provide a semiconductor device having a reduced dislocation density and excellent crystal quality, and an epitaxial substrate used for the same.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing one manufacturing process in the case of forming an intermediate layer on an underlayer using the ELO technique.

FIG. 2 is a cross-sectional view showing a manufacturing step that is subsequent to the manufacturing step shown in FIG.

FIG. 3 is a sectional view showing an example of an epitaxial substrate of the present invention.

FIG. 4 is a cross-sectional view showing one manufacturing step in the method for manufacturing an epitaxial substrate of the present invention.

5A to 5C are cross-sectional views showing a manufacturing process subsequent to the manufacturing process shown in FIGS.

[Explanation of symbols]

1, 11 Base material, 2, 12 Underlayer, 3, 13 Intermediate layer, 4, 14 Mask, 10 Epitaxial substrate, 1
5 facets, 16 initial epitaxial growth layers

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Kazumasa Hiramatsu             1-4-22 Shibata, Yokkaichi-shi, Mie Prefecture (72) Inventor Hideto Miyake             372-303 Nomura Town, Hisai City, Mie Prefecture (72) Inventor Yoshihiro Kida             181-1 Kurimanakayamacho, Tsu City, Mie Prefecture             Male B206 F-term (reference) 4G077 AA03 BE13 DB08 ED06 EE06                       EE07 EF03 TB05 TC14 TC16                       TC19                 5F045 AA04 AB09 AB17 AC08 AC12                       AD14 AE23 AE25 AF09 AF13                       BB12 CA09 DA53 DA67 DB02                       DB04

Claims (18)

[Claims] 1. A base material made of a single crystal material, a base layer made of an Al-containing first group III nitride formed adjacent to the base material, and formed adjacent to the base layer. Second II
An intermediate layer made of a group I nitride, and a semiconductor element layer made of a third group III nitride formed adjacent to the intermediate layer, wherein the intermediate layer is inclined at a constant angle from the underlayer. A semiconductor device having a facet that rises up. 2. The first group III nitride forming the underlayer is Alx1Gay1Inz1N (x1 + y1 + z
The semiconductor element according to claim 1, having a composition of 1 = 1, x1 ≧ 0.5, y1 ≧ 0, z1 ≧ 0). 3. The semiconductor device according to claim 2, wherein the first group III nitride forming the underlayer has a composition of AlN. 4. The full width at half maximum of the X-ray rocking curve of the (002) plane of the first group III nitride constituting the underlayer is 100 seconds or less.
3. The semiconductor device according to any one of 3 above. 5. The second group III nitride constituting the intermediate layer is Alx2Gay2Inz2N (x2 + y2 + z
2 = 1, x2 ≧ 0, y2 ≧ 0, z2 ≧ 0), and in the composition with the first group III nitride constituting the underlayer, the relationship of x2 ≦ x1-0.1 The semiconductor element according to any one of claims 2 to 4, characterized in that 6. The substrate is made of sapphire single crystal and has a nitrogen content of 2 at a depth of 1 nm from the main surface of the substrate.
The semiconductor device according to any one of claims 1 to 5, wherein the semiconductor device has a surface nitrided layer of at least atomic%. 7. A base material made of a single crystal material, a base layer made of an Al-containing first group III nitride formed adjacent to the base material, and formed adjacent to the base layer. Second II
An epitaxial substrate, comprising: an intermediate layer made of a group I nitride, wherein the intermediate layer has a facet that is inclined and rises at a constant angle from the underlayer. 8. The first group III nitride constituting the underlayer is Alx1Gay1Inz1N (x1 + y1 + z
The epitaxial substrate according to claim 7, having a composition of 1 = 1, x1 ≧ 0.5, y1 ≧ 0, z1 ≧ 0). 9. The epitaxial substrate according to claim 8, wherein the first group III nitride forming the underlayer has a composition of AlN. 10. The full width at half maximum of the X-ray rocking curve of the (0002) plane of the first group III nitride forming the underlayer is 100 seconds or less.
10. The epitaxial substrate according to any one of items 9 to 9. 11. The second group III nitride constituting the intermediate layer is Alx2Gay2Inz2N (x2 + y2 +).
z2 = 1, x2 ≧ 0, y2 ≧ 0, z2 ≧ 0), and in the composition with the first group III nitride constituting the underlayer, the relationship of x2 ≦ x1-0.1 The epitaxial substrate according to any one of claims 8 to 10, characterized in that: 12. The substrate is made of sapphire single crystal,
The epitaxial substrate according to claim 7, further comprising a surface nitrided layer having a nitrogen content of 2 atomic% or more at a depth of 1 nm from the main surface of the base material. 13. A base material made of a single crystal material, an underlayer made of an Al-containing first group III nitride formed adjacent to the base material, and formed adjacent to the underlayer. Second
What is claimed is: 1. A method of manufacturing a semiconductor device, comprising: an intermediate layer made of a group III nitride; and a semiconductor element layer made of a third group III nitride formed adjacent to the intermediate layer, wherein the intermediate layer comprises: After forming a predetermined mask on the underlayer, after performing epitaxial growth on the underlayer through the mask so as to have facets that are inclined and risen from the underlayer at a constant angle, the facets are formed. Buried,
A method of manufacturing a semiconductor device, which is characterized in that it is formed by epitaxial growth so as to be planarized. 14. The mask has a longitudinal direction of <10-10 of the first group III nitride constituting the underlayer.
> Is formed so as to be parallel to the direction,
The method for manufacturing a semiconductor device according to claim 13. 15. The substrate comprises a sapphire single crystal,
A surface nitriding layer having a nitrogen content of 2 atomic% or more at a depth of 1 nm from the main surface of the base material is formed by subjecting the main surface of the base material to a surface nitriding treatment. 15. The method for manufacturing a semiconductor device according to claim 13 or 14. 16. A base material made of a single crystal material, a base layer made of an Al-containing first group III nitride formed adjacent to the base material, and formed adjacent to the base layer. Second
A method of manufacturing an epitaxial substrate comprising an intermediate layer comprising a group III nitride, wherein the intermediate layer, after forming a predetermined mask on the underlying layer, through the mask on the underlying layer, The epitaxial layer is formed so that it has a facet that is inclined and rises at a constant angle from the underlying layer, and then the facet is embedded and formed so as to be planarized.
Method for manufacturing epitaxial substrate. 17. The mask has a longitudinal direction of <10-10 of the first group III nitride which constitutes the underlayer.
17. It is formed parallel to the> direction.
A method for manufacturing an epitaxial substrate according to. 18. The substrate comprises sapphire single crystal,
A surface nitriding layer having a nitrogen content of 2 atomic% or more at a depth of 1 nm from the main surface of the base material is formed by subjecting the main surface of the base material to a surface nitriding treatment. The method for manufacturing an epitaxial substrate according to claim 16 or 17.