JP6187064B2 - Periodic table group 13 metal nitride semiconductor substrate - Google Patents

Description

  The present invention relates to a periodic table group 13 metal nitride semiconductor substrate. Specifically, a periodic table group 13 metal nitride crystal grown in the m-axis direction and a periodic table grown in a direction inclined from the m-axis to the c-axis direction by an angle of 10 ° to 80 °. The present invention relates to a periodic table group 13 metal nitride semiconductor substrate having an outer region made of a group 13 metal nitride crystal.

Conventionally, periodic table group 13 metal nitrides such as gallium nitride (GaN) -based compounds have been used as semiconductor materials for periodic table group 13 metal nitride semiconductor substrates, and periodic table group 13 metal nitride semiconductors. Substrates are used in various devices such as light emitting devices. In recent years, the periodic table group 13 metal nitride semiconductor substrate is used not only for light emitting devices but also for power semiconductor elements (power devices). Therefore, development of a periodic table group 13 metal nitride semiconductor substrate capable of withstanding high pressure and large current is underway.
A single crystal of nitride such as gallium nitride or aluminum nitride can be obtained by growing the crystal using an ammonothermal method or the like. The ammonothermal method is a method for producing a desired material by using a dissolution-precipitation reaction of raw materials using a solvent containing nitrogen such as ammonia in a supercritical state and / or a subcritical state. When applied to crystal growth, this is a method in which crystals are precipitated by generating a supersaturated state due to a temperature difference utilizing the temperature dependence of the solubility of a raw material in a solvent such as ammonia.

  Conventionally, a group 13 metal nitride semiconductor substrate of the periodic table has been used in many cases having a C-plane which is a polar plane as a main surface. However, in this case, due to the inherent characteristics of the Group 13 nitride crystal such as GaN, there is a problem that the influence of the piezo electric field is increased and the efficiency of the light emitting element is lowered. In addition, crystal defects such as threading dislocations may occur in a semiconductor substrate having a C-plane as a main surface, and the dislocation density may increase.

In order to solve these problems, it has been studied to produce a light-emitting device using a substrate having a nonpolar plane other than the C plane or a semipolar plane as a main plane. Therefore, it is required to manufacture a substrate having a large nonpolar surface or semipolar surface as a main surface from which a device can be manufactured. For example, Patent Documents 1 to 3 disclose that crystal growth is performed using a seed crystal having an M plane as a growth main surface.
In Patent Document 1, the side surfaces of the obtained grown crystal are the A plane and the C plane, and the main surface of the grown crystal is composed only of the M plane obtained by lateral growth. Similarly, Patent Documents 2 and 3 only describe that crystal growth is performed with the main surface as the M-plane. In Patent Document 3, an alkali mineralizer is preferably used as a mineralizer used during crystal growth.

International Publication 2010/005914 Pamphlet Special table 2011-521878 gazette Special table 2009-541997

  In order to efficiently obtain a periodic table group 13 metal nitride semiconductor substrate (hereinafter also referred to as group 13 nitride semiconductor substrate) having an M plane as a main surface, a group 13 nitride having the M plane as a main growth surface It is necessary to grow crystals. However, the rate of crystal growth in the m-axis direction with the M plane as the growth plane is slow, and it is difficult to increase the size of the semiconductor substrate with the M plane as the main plane. Furthermore, the semiconductor substrate having the M plane as the main surface has a problem that the manufacturing cost per unit area becomes very high because the size is small and the crystal growth rate is slow.

  Further, in the conventional method of growing a group 13 nitride crystal having the M plane as the growth main surface, a nitride semiconductor bar is cut out from a primary wafer formed by performing thick film growth using the C plane as a growth plane. A nitride semiconductor has been regrown on a substrate arranged so that the surface becomes the upper surface. That is, there has been a problem that crystals having an M-plane as a main surface cannot be grown on the substrate under the same conditions as the substrate manufacturing conditions. For this reason, there was a problem that a semiconductor substrate having the M surface as the main surface could not be obtained efficiently.

  Therefore, in order to solve the problems of the prior art, the inventors of the present application are a group 13 nitride semiconductor substrate having an M plane as a main surface, the main surface size of the substrate being large, and high quality crystals. In order to provide a Group 13 nitride semiconductor substrate that is made of the above and has a reduced manufacturing cost, studies have been conducted.

As a result of intensive studies to solve the above-mentioned problems, the inventors of the present application have found that a central region made of a group 13 nitride crystal grown in the m-axis direction and 10 ° to 80 ° from the m-axis to the c-axis direction. By forming a group 13 nitride semiconductor substrate having an outer region made of a group 13 nitride crystal grown in a direction inclined at an angle of °, the M-plane area of the semiconductor substrate can be increased, and high It has been found that a high quality region composed of quality crystals can be secured in a wide proportion.
Specifically, the present invention has the following configuration.

[1] A periodic table group 13 metal nitride semiconductor substrate having an outer region and a central region adjacent to the outer region, the main surface of which is an M plane, and the central region has grown in the m-axis direction It consists of a periodic table group 13 metal nitride crystal, and the outer region consists of a periodic table group 13 metal nitride crystal grown in a direction inclined at an angle of 10 ° to 80 ° from the m-axis to the c-axis direction. A periodic table group 13 metal nitride semiconductor substrate characterized by the following.
[2] The description of [1], wherein the outer region includes an outer first region and an outer second region, and the central region is a region sandwiched between the outer first region and the outer second region. A periodic table group 13 metal nitride semiconductor substrate.
[3] The periodic table group 13 metal nitride semiconductor substrate according to [1] or [2], wherein the outer region is made of a periodic table group 13 metal nitride crystal grown using a semipolar plane as a growth surface.
[4] The periodic table group 13 metal nitride semiconductor substrate according to [3], wherein the semipolar plane includes at least one of a [10-11] plane and a [10-1-1] plane.
[5] The outer first region is made of a periodic table group 13 metal nitride crystal grown with the [10-1-1] plane as a growth plane, and the outer second region has a [10-11] plane as a growth plane. The periodic table group 13 metal nitride according to [2], wherein the area of the outer first region on the main surface is larger than the area of the outer second region. Semiconductor substrate.
[6] The ratio of the area of the outer region to the main surface in the area of the entire main surface of the Group 13 metal nitride semiconductor substrate of the periodic table is 40% or less, [1] to [5] 12. A periodic table group 13 metal nitride semiconductor substrate according to item 1.
[7] The periodic table group 13 metal nitride semiconductor substrate according to any one of [1] to [6], wherein chromaticity of the outer region is different from chromaticity of the central region.
[8] The outer region and the central region contain fluorine atoms in a periodic table group 13 metal nitride crystal, and the concentration of the fluorine atoms is 1 × 10 ¹⁶ atoms / cm ³ or more. The periodic table group 13 metal nitride semiconductor substrate according to any one of [7].
[9] The periodic table group 13 metal nitride semiconductor substrate according to [8], wherein the concentration of fluorine atoms in the outer region is 110% or more of the concentration of fluorine atoms in the central region.
[10] The outer region and the central region include oxygen atoms in a periodic table group 13 metal nitride crystal, and the outer region is grown as a growth surface having a [10-1-1] plane as the outer region. Any one of [1] to [9], which has an outer first region composed of a group metal nitride crystal, and the concentration of oxygen atoms in the outer first region is 130% or less of the concentration of oxygen atoms in the central region. A periodic table group 13 metal nitride semiconductor substrate according to claim 1.
[11] The outer region further includes an outer second region made of a periodic table group 13 metal nitride crystal grown using the [10-11] plane as a growth surface, and the concentration of oxygen atoms in the outer second region Is a group 13 metal nitride semiconductor substrate of the periodic table according to [10], which is 150% or more of the concentration of oxygen atoms in the central region.
[12] The outer region and the central region include a hydrogen atom in a periodic table group 13 metal nitride crystal, and the outer region grows with the [10-1-1] plane as a growth surface. [1] to [11] having an outer first region made of group metal nitride crystal, wherein the concentration of hydrogen atoms in the outer first region is 130% or less of the concentration of hydrogen atoms in the central region. The periodic table group 13 metal nitride semiconductor substrate according to claim 1.
[13] The outer region further includes an outer second region made of a periodic table Group 13 metal nitride crystal grown using the [10-11] plane as a growth surface, and the concentration of hydrogen atoms in the outer second region Is a group 13 metal nitride semiconductor substrate of the periodic table according to [12], which is 110% or more of the concentration of hydrogen atoms in the central region.
[14] The periodic table according to any one of [1] to [13], wherein the periodic table group 13 metal nitride crystal in the periodic table group 13 metal nitride semiconductor substrate is formed by an ammonothermal method. Group 13 metal nitride semiconductor substrate.
[15] An epitaxial wafer comprising the periodic table group 13 metal nitride semiconductor substrate according to any one of [1] to [14] and an epitaxially grown film.

According to the present invention, it is possible to obtain a semiconductor substrate having an M surface as a main surface and a large main surface area of the substrate. In addition, a high-quality region made of high-quality crystals can be secured in a wide ratio in the main surface of the substrate.
Further, according to the present invention, the manufacturing cost per unit area of the semiconductor substrate can be suppressed.

  Furthermore, when an epitaxial growth film is grown using the group 13 nitride semiconductor substrate of the present invention as a base substrate, the size of the obtained epitaxial wafer can be increased. This epitaxial wafer is suitably used for a light emitting device, a power semiconductor element (power device) and the like.

FIG. 1 is a schematic diagram showing a unit cell having a crystal structure of a group 13 nitride semiconductor. FIG. 2 shows a schematic view of the group 13 nitride semiconductor substrate of the present invention. FIG. 3 is a schematic diagram showing an embodiment of a base substrate (seed crystal) used for crystal growth. FIG. 4 is a schematic view of an example of a group 13 nitride crystal mass used in the present invention having an M plane as a main surface. FIG. 5 is a schematic cross-sectional view of a group 13 nitride crystal mass used in the present invention. FIG. 6 is a schematic cross-sectional view of a group 13 nitride crystal mass used in the present invention. FIG. 7 is a schematic view of a crystal manufacturing apparatus that can be used in the present invention.

  Hereinafter, the present invention will be described in detail. The description of the constituent elements described below may be made based on representative embodiments and specific examples, but the present invention is not limited to such embodiments. In the present specification, a numerical range expressed using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value.

(Group 13 nitride semiconductor substrate)
The present invention relates to a periodic table group 13 metal nitride semiconductor substrate (hereinafter also referred to as group 13 nitride semiconductor substrate). The periodic table group 13 metal nitride semiconductor substrate of the present invention has an outer region and a central region adjacent to the outer region, and the main surface is an M plane. The central region is composed of a periodic table group 13 metal nitride crystal grown in the m-axis direction. The outer region is composed of a periodic table group 13 metal nitride crystal grown in a direction inclined at an angle of 10 ° to 80 ° in the c-axis direction from the m-axis.

As shown in FIG. 1, the group 13 nitride compound used as the material of the group 13 nitride semiconductor substrate according to the present invention has a hexagonal crystal structure. In this specification, the “principal surface” refers to the widest surface in the crystal, and usually the surface on which crystal growth is to be performed. The “side surface” means a surface that intersects the main surface, and may or may not be adjacent to the main surface.
In this specification, the “C plane” is a plane equivalent to the {0001} plane in a hexagonal crystal structure (wurtzite type crystal structure), and is a polar plane. For example, it refers to the (0001) plane shown in FIG. 1 and the (000-1) plane opposite to the (0001) plane, and may be referred to as + C plane and −C plane, respectively. In the group 13 nitride crystal, the + C plane is a group 13 plane of the periodic table and the −C plane is a nitrogen plane, and in gallium nitride, it corresponds to a Ga plane or an N plane, respectively.
Further, in this specification, the “M plane” refers to {1-100} plane, {01-10} plane, [−1010] plane, {−1100} plane, {0-110} plane, {10-10 } Non-polar planes comprehensively represented as planes, specifically (1-100) plane, (01-10) plane, (-1010) plane, (-1100) plane, (0-110). ) Plane and (10-10) plane. Further, in this specification, the “A plane” means {2-1-10} plane, {-12-10} plane, {-1-120} plane, {-2110} plane, {1-210} plane. , {11-20} plane which is comprehensively represented as a plane. Specifically, the (11-20) plane, (2-1-10) plane, (-12-10) plane, (-1-120) plane, (-2110) plane, (1-210) plane means. In this specification, “c-axis”, “m-axis”, and “a-axis” mean axes perpendicular to the C-plane, M-plane, and A-plane, respectively.
In the present specification, the “nonpolar plane” means a plane in which both a Group 13 element and a nitrogen element are present on the surface and the abundance ratio thereof is 1: 1. Specifically, the M surface and the A surface can be mentioned. In the present specification, the term “polar plane” or “non-polar plane” includes a plane within a range having an off angle of less than 10 ° from each crystal axis measured with an accuracy within ± 0.01 °. The off angle is preferably within 5 °, more preferably within 3 °. Similarly, the c-axis, m-axis, and a-axis also include axial directions within a range having an off angle.

In this specification, the “semipolar plane” means, for example, that when the group 13 nitride of the periodic table is hexagonal and the main surface is represented by (hklm), m = 0 except for the [0001] plane It's not a side. That is, it refers to a plane that is inclined with respect to the (0001) plane and is not a nonpolar plane. It means a surface in which only one of the group 13 element and nitrogen element in the periodic table or the C surface is present on the surface, and the abundance ratio is not 1: 1. h, k, l and m are each independently preferably an integer of -5 to 5, more preferably an integer of -2 to 2, and preferably a low index surface. .
Note that in this specification, a semi-polar plane is sometimes referred to as an S plane. In addition, an axis perpendicular to the semipolar plane may be expressed as “s-axis”. Therefore, the direction inclined at an angle of 10 ° to 80 ° from the m-axis to the c-axis direction coincides with the s-axis direction.

  Examples of the group 13 nitride semiconductor substrate include a periodic table group 13 metal nitride substrate represented by GaN and AlN. Examples of the periodic table group 13 metal nitride include GaN, AlN, InN, and mixed crystals thereof. Examples of the mixed crystal include AlGaN, InGaN, AlInN, and AlInGaN. Preferred is a mixed crystal containing GaN and Ga, and more preferred is GaN.

  FIG. 2 shows a schematic view of the group 13 nitride semiconductor substrate of the present invention. As shown in FIGS. 2A and 2B, the group 13 nitride semiconductor substrate of the present invention has an outer region S and a central region M. The central region M is a region adjacent to the outer region S. As shown in FIG. 2A, the group 13 nitride semiconductor substrate may have a square shape, or may have a circular shape as shown in FIG.

  Moreover, the outer side area | region S is good also as having an outer side 1st area | region and an outer side 2nd area | region. As shown in FIGS. 2C, 2D, and 2E, the outer region S has an outer first region S1 and an outer second region S2 outside the central region M. The central region is a region sandwiched between the outer first region and the outer second region.

The shape of the main surface of the central region is not particularly limited, but it is preferable to be adjacent to the outer region via a straight line. be able to. The outer region exists in a region adjacent to the central region, and when the central region has a shape obtained by cutting a part of a circle with a straight line, the outer region exists in a region that is in contact with a part of the straight line. When the outer region includes the outer first region and the outer second region, the main surface of the central region preferably has a shape having two opposing sides, and the group 13 nitride semiconductor substrate of the present invention 2 is a quadrangle, the center region is preferably formed from two opposing sides as shown in FIGS. 2C and 2D, and the group 13 nitride semiconductor substrate of the present invention is circular. As shown in FIG. 2 (e), it is preferable that the central region has a shape obtained by cutting the upper and lower sides of the circle with a straight line.
Further, when the shape of the central region is a quadrangle, the two opposing sides may have the same length or different lengths. All four sides constituting the central region may have the same length or may have different lengths. When the shape of the main surface of the central region is a rectangle, the outer first region and the outer second region may be provided on the long side opposite to the main surface as shown in FIG. Although it may be provided on the opposite short side as in d), it is preferably provided on the opposite long side.

  In the group 13 nitride semiconductor substrate of the present invention, after the outer region S is grown, the group 13 nitride semiconductor substrate of the present invention can be further used as a base substrate. Further, a part of the outer region S can be scraped off or polished. For example, a portion inferior in crystal quality in the outer region can be scraped off. As a result, the size of the main surface of the group 13 nitride semiconductor substrate of the present invention is reduced, but it is possible to reduce the proportion of the area of the outer region of the entire main surface that is inferior in crystal quality.

  The principal surface of the periodic table group 13 metal nitride semiconductor substrate according to the present invention is an M-plane. That is, the main surface of the central region and the outer region is the M plane. Thus, by making the main surface into M plane, a group 13 nitride semiconductor crystal shows favorable crystallinity. By using the M plane as the main surface, the dislocation density penetrating the main surface of the substrate can be reduced, so that a group 13 nitride semiconductor crystal with few threading dislocations and reduced crystal defects can be obtained. Thereby, a high-quality group 13 nitride semiconductor substrate with few crystal defects can be obtained.

  The central region is composed of a periodic table group 13 metal nitride crystal grown in the m-axis direction. That is, the central region is composed of a growth crystal of Group 13 metal nitride of the periodic table grown with the M plane as the growth plane. In this specification, the growth in the m-axis direction is sometimes referred to as “M-plane growth”, and the growth rate in the m-axis direction is sometimes referred to as “M-plane growth rate”. The central region may include not only crystals grown strictly in the m-axis direction but also crystals grown in a direction having an off angle of less than 10 ° from the m-axis. This is referred to as “Group 13 nitride crystal grown in the m-axis direction”. The off angle is preferably 5 ° or less, and more preferably 3 ° or less. However, the central region preferably has a flat M surface as a growth surface. Even in the case where the main surface of the base substrate is an M-plane having an off angle, the crystal surface appearing in a growth crystal lump described later is preferably a flat M-plane having a very small off-angle.

  The outer region is composed of a periodic table group 13 metal nitride crystal grown in a direction inclined at an angle of 10 ° to 80 ° in the c-axis direction from the m-axis. That is, the outer region is composed of a growth crystal of a periodic table group 13 metal nitride grown using a semipolar plane as a growth plane. The outer region grows in a direction inclined at an angle of 10 ° to 80 ° from the m-axis to the c-axis, and forms a periodic table group 13 metal nitride crystal so as to spread laterally including the M-plane. The area of the M surface in the outer region can be increased. In the present specification, growing in the s-axis direction including a direction inclined at an angle of 10 ° to 80 ° from the m-axis to the c-axis direction is referred to as “semipolar plane (S plane) growth”. The growth rate that grows in the s-axis direction may be referred to as a “semipolar plane (S plane) growth rate”.

  Even if the outer region is formed of a periodic table group 13 metal nitride crystal grown in a direction inclined at an angle of 10 ° to 80 ° in the + c axis direction from the m-axis, it is 10 ° to 80 ° in the −c axis direction. Periodic Table Group 13 metal nitride crystals grown in a direction inclined at an angle of 10 ° to 80 °, but grown in a direction inclined at an angle of 10 ° to 80 ° with respect to the −c-axis direction. It is preferably made of a metal nitride crystal. This is because a region grown in a direction inclined at an angle of 10 ° to 80 ° with respect to the −c axis direction has a small impurity content and good crystal quality. Thus, by growing in a direction inclined at an angle of 10 ° to 80 ° with respect to the −c axis direction, a high-quality crystal with reduced impurity incorporation can be efficiently obtained.

Moreover, the outer region in the group 13 nitride substrate of the present invention may expose a semipolar surface as a side surface. Since the growth surface of the periodic table group 13 metal nitride crystal in the outer region is a semipolar surface, in the substrate obtained by slicing the M surface as the main surface, the semipolar surface that was the growth surface is the main surface. It is exposed on the surface of the Group 13 nitride substrate of the invention.
The periodic table group 13 metal nitride crystal grown using the semipolar plane as the growth plane has the semipolar plane in a part of the crystal even after the growth. Each of these semipolar surfaces is included in a part of the exposed region of the outer region. Here, the exposed region refers to a surface region of the outer region and includes a part of the edge. By obtaining the group 13 nitride substrate of the present invention in which the outer region grows with the semipolar plane as the growth plane and the M plane as the principal plane so as to include the semipolar plane, the M plane area of the outer region is further increased Can be bigger.
Note that the outer region may not include a semipolar surface by scraping or polishing the outer periphery of the Group 13 metal nitride semiconductor substrate of the periodic table.

  The semipolar plane as the growth plane of the outer region preferably includes at least one of the [10-11] plane and the [10-1-1] plane. When the semipolar plane includes these planes, the growth rate can be particularly stably increased, so that the manufacturing efficiency can be further increased and the size of the group 13 nitride semiconductor substrate can be increased. Especially, since the impurity concentration in the grown periodic table group 13 metal nitride crystal is low, it is more preferable that the semipolar plane as the growth plane of the outer region is a [10-1-1] plane. As a result, it is possible to obtain a substrate having a larger M plane with higher quality crystals.

  The main surface of the outer region is an M surface, and these M surfaces are continuous with the M surface of the central region and are a series of planes with the M surface as the main surface. Thereby, the area of the periodic table group 13 metal nitride semiconductor substrate having the M plane as the main surface can be increased.

The ratio of the area of the outer region to the main surface in the area of the entire main surface of the Group 13 metal nitride semiconductor substrate of the periodic table is preferably 40% or less. The proportion of the area of the outer region on the main surface may be 40% or less, more preferably 20% or less, and still more preferably 10% or less. Further, it is preferably 2% or more, more preferably 3% or more, and further preferably 5% or more.
By making the ratio of the area of the outer region in the main surface less than or equal to the above upper limit value, the ratio of the central region grown in the m-axis direction can be made a certain level or more, and there are fewer crystal defects and higher quality. A group 13 nitride semiconductor substrate can be obtained. Further, by setting the ratio of the area of the outer region in the main surface to the above lower limit value or more, the size of the semiconductor substrate having the M surface as the main surface can be further increased.
When the outer region has the outer first region and the outer second region, the area of the outer region on the main surface is the sum of the areas of the main surface of the outer first region and the main surface of the outer second region on the outer surface. Refers to the area.

  The outer first region is composed of a periodic table group 13 metal nitride crystal grown using the [10-1-1] plane as a growth plane, and the outer second region is a periodic table grown using the [10-11] plane as a growth plane. When the group 13 metal nitride crystal is used, the area of the outer first region on the main surface is preferably larger than the area of the outer second region. More preferably, there is no outer second region. This is because the periodic table group 13 metal nitride crystal grown using the [10-1-1] plane as a growth plane has less crystallinity because of less impurities incorporated during the growth, and the [10-11] plane is improved. This is because the periodic table group 13 metal nitride crystal grown as a growth surface tends to take in impurities during growth, and thus has poor crystallinity. Therefore, by increasing the area of the first outer region, it is possible to increase the size of the M surface, which is the main surface, and to obtain a substrate having excellent crystallinity.

The chromaticity of the outer region and the chromaticity of the central region may be different. Specifically, the chromaticity of the outer region may be higher than the chromaticity of the central region. That is, it may be colored brown based on the outer region. For example, the transmittance at a wavelength of 400 to 600 nm is preferably higher in the central region than in the outer region. This is considered to be due to the difference in the amount of oxygen, fluorine, hydrogen and other impurities taken up when the growth surface has the M-plane and the semipolar surface.
By coloring the range grown with the semipolar plane as the growth plane, the central region and the outer region can be distinguished and recognized. This makes it possible to use each area properly depending on the application.

The outer region may include fluorine atoms in the periodic table group 13 metal nitride crystal. In this case, the concentration of fluorine atoms contained in the periodic table group 13 metal nitride crystal constituting the outer region is preferably 1 × 10 ¹⁶ atoms / cm ³ or more, and preferably 5 × 10 ¹⁶ atoms / cm ³ or more. It is more preferable that Further, the fluorine concentration is preferably 1 × 10 ²¹ atoms / cm ³ or less, and more preferably 1 × 10 ²⁰ atoms / cm ³ or less. By making the fluorine concentration in the group 13 metal nitride crystal of the periodic table within the above range, the total area of the outer region on the main surface can be easily reduced to 40% or less with respect to the entire main surface of the substrate. Can be controlled.

Similarly to the outer region, the central region may include fluorine atoms in the periodic table group 13 metal nitride crystal. In this case, the concentration of fluorine atoms contained in the periodic table Group 13 metal nitride crystal constituting the central region is preferably 1 × 10 ¹⁶ atoms / cm ³ or more, and preferably 3 × 10 ¹⁶ atoms / cm ^3. More preferably. Further, the fluorine concentration is preferably 1 × 10 ²¹ atoms / cm ³ or less, and more preferably 1 × 10 ²⁰ atoms / cm ³ or less.

The concentration of fluorine atoms contained in the periodic table group 13 metal nitride crystal constituting the central region is lower than the concentration of fluorine atoms contained in the periodic table group 13 metal nitride crystal constituting the outer region. Is preferred. Further, the concentration of fluorine atoms in the outer region is preferably 110% or more and more preferably 180% or less of the concentration of fluorine atoms in the central region. Here, the concentration of fluorine atoms is indicated by the number of atoms contained in 1 cm ³ .

Further, the outer region and the central region may contain oxygen atoms in the periodic table group 13 metal nitride crystal. The concentration of oxygen atoms in the outer region grew from the m-axis in a direction inclined at an angle of 10 ° to 80 ° in the −c-axis direction or in a direction inclined at an angle of 10 ° to 80 ° in the + c-axis direction. Tend to be different. The concentration of oxygen atoms in the outer region grown in a direction inclined at an angle of 10 ° to 80 ° from the m-axis to the −c-axis direction tends to be equal to or less than the concentration of oxygen atoms in the central region. Further, the concentration of oxygen atoms in the outer region grown in a direction inclined at an angle of 10 ° to 80 ° in the + c-axis direction tends to be equal to or higher than the concentration of oxygen atoms in the central region. Further, an outer region grown in a direction inclined at an angle of 10 ° to 80 ° from the m axis to the −c axis direction, and an outer region grown in a direction inclined at an angle of 10 ° to 80 ° from the m axis to the + c axis direction. Comparing the concentration of oxygen atoms with the region, the outer region grown in the direction inclined from the m-axis to the −c-axis direction is lower, and a high-purity and high-quality crystal can be obtained.
When the outer region has an outer first region made of a group 13 metal nitride crystal of the periodic table grown with the [10-1-1] plane as a growth surface, the concentration of oxygen atoms in the outer first region is the central region. The oxygen atom concentration is preferably 130% or less, more preferably 100% or less. Further, when the outer region has an outer second region made of a periodic table group 13 metal nitride crystal grown with the [10-11] plane as a growth surface, the concentration of oxygen atoms in the outer second region Is preferably 150% or more of the concentration of oxygen atoms in the central region, and preferably 190% or less.
The oxygen atom concentration is indicated by the number of atoms contained in 1 cm ³ .

Further, the outer region and the central region may contain hydrogen atoms in the periodic table group 13 metal nitride crystal. The concentration of hydrogen atoms in the outer region grows in a direction inclined at an angle of 10 ° to 80 ° in the −c axis direction from the m axis, or grows in a direction inclined at an angle of 10 ° to 80 ° in the + c axis direction. Tend to be different. The concentration of hydrogen atoms in the outer region grown in a direction inclined at an angle of 10 ° to 80 ° from the m-axis to the −c-axis direction tends to be equal to or less than the concentration of hydrogen atoms in the central region. Further, the concentration of hydrogen atoms in the outer region grown in a direction inclined at an angle of 10 ° to 80 ° in the + c-axis direction tends to be higher than the concentration of hydrogen atoms in the central region. Further, an outer region grown in a direction inclined at an angle of 10 ° to 80 ° from the m axis to the −c axis direction, and an outer region grown in a direction inclined at an angle of 10 ° to 80 ° from the m axis to the + c axis direction. Comparing the concentration of hydrogen atoms with the region, the outer region grown in the direction inclined from the m-axis to the −c-axis direction is lower, and a high-purity and high-quality crystal can be obtained.
When the outer region has an outer first region made of a group 13 metal nitride crystal of the periodic table grown with the [10-1-1] plane as a growth surface, the concentration of hydrogen atoms in the outer first region is the central region. The concentration of hydrogen atoms is preferably 130% or less, more preferably 100% or less. Further, when the outer region has an outer second region made of a periodic table group 13 metal nitride crystal grown using the [10-11] plane as a growth surface, the concentration of hydrogen atoms in the outer second region is It is preferably 110% or more of the concentration of hydrogen atoms in the central region, and preferably 150% or less.
The concentration of hydrogen atoms is indicated by the number of atoms contained in 1 cm ³ .

In the periodic table group 13 metal nitride crystal in the outer region, the peak top of the yellow luminescence of PL wavelength is preferably equal to or longer than that of the central region. Moreover, it is preferable that the band edge emission wavelength in the outer region is equal to or longer than that in the central region.
In particular, an outer first region made of a group 13 metal nitride crystal of the periodic table grown with the [10-1-1] plane as the growth surface as the outer region, and a periodic table grown with the [10-11] plane as the growth surface. In the case of having an outer second region made of a Group 13 metal nitride crystal, the peak top of the yellow luminescence of the PL wavelength of the outer first region is equivalent to that of the central region, and the PL wavelength of the outer second region is The peak top of yellow luminescence preferably has a longer wavelength than that of the central region. The same applies to the band edge emission wavelength. When such a tendency exists, the PL mapping results in the outer first region and the central region having good crystal quality and the outer second region having inferior crystal quality among the regions included in the group 13 nitride semiconductor substrate. Identification becomes easy.

  The M-plane of the group 13 nitride semiconductor substrate according to the present invention may have an off-angle in the c-axis direction, and in that case, preferably has an off-angle in the −c-axis direction. The off-angle refers to an angle representing a deviation from a predetermined low index surface. In the present invention, the growth main surface of the group 13 nitride semiconductor substrate having an off angle is a surface inclined at a predetermined angle with respect to the M plane.

  The absolute value of the off angle is preferably less than 10 °, more preferably 5 ° or less, and even more preferably 4 ° or less. By adjusting the off-angle in the c-axis direction to be within the above range, high-quality crystals can be obtained when crystal growth of an epitaxial growth film or the like is performed on the group 13 nitride semiconductor substrate of the present invention. it can. Furthermore, it is preferable because the surface of the epitaxial growth film can be kept flat by adjusting the off angle of the main surface of the group 13 nitride semiconductor substrate.

  The thickness of the group 13 nitride semiconductor substrate can be appropriately determined by design. For example, when used as an epitaxial wafer, the thickness of the substrate is preferably 100 μm or more, more preferably 200 μm or more, and further preferably 250 μm or more. In the epitaxial wafer, the thickness of the substrate is preferably 700 μm or less, more preferably 650 μm or less, and further preferably 500 μm or less.

The concentration of the metal and alkali metal of the group 13 nitride semiconductor substrate is preferably 1 × 10 ¹⁶ atoms / cm ³ or less, and more preferably 1 × 10 ¹⁵ atoms / cm ³ or less. Here, the said density | concentration points out the total density | concentration of the density | concentration of a metal and an alkali metal. By setting the concentration of the metal and alkali metal of the group 13 nitride semiconductor substrate in the above range, the ratio of the central region and the outer region included in the group 13 nitride semiconductor substrate can be made a more preferable ratio.

The dislocation density of the group 13 nitride semiconductor substrate is preferably 1 × 10 ⁷ cm ⁻³ or less, more preferably 1 × 10 ⁶ m ⁻³ or less, and 1 × 10 ³ cm ⁻³ or less. More preferably it is. The dislocation density may be 0 as long as it is within the above range.

  A group 13 nitride semiconductor substrate according to the present invention is obtained by growing a group 13 nitride semiconductor crystal on a base substrate to form a group 13 nitride growth crystal mass (in this specification, a group 13 nitride). May be referred to as a crystal lump), and obtained by slicing the grown crystal lump.

(Base substrate (seed crystal))
The base substrate functions as a seed crystal. In the present invention, in order to obtain a Group 13 nitride semiconductor substrate, it is preferable to use a seed crystal having an M plane as a main surface. The main surface here means a surface having the maximum area among the surfaces constituting the crystal.
As shown in FIG. 3, the base substrate 40 is a plate-like group 13 nitride seed crystal having a front-side main surface 41 and a back-side main surface. A group 13 nitride semiconductor crystal can be grown on the underlying substrate to obtain a grown crystal mass having the M-plane as the main surface on the front side. The plane orientation of the base substrate is not limited to the above-described mode, but may have an off angle of ± 15 ° from the M plane, and the off angle is preferably within ± 10 °.

The base substrate has a hexagonal crystal structure. As the group 13 nitride seed crystal, a single crystal of nitride grown as a growth crystal is used. Specific examples of the group 13 nitride seed crystals include nitride single crystals such as gallium nitride (GaN), aluminum nitride (AlN), indium nitride (InN), or mixed crystals thereof.
The base substrate can be determined in consideration of lattice matching with the grown crystal. For example, as a seed crystal, a single crystal obtained by epitaxial growth on a heterogeneous substrate such as sapphire and then exfoliated, a single crystal obtained by crystal growth of Na, Li, Bi as a flux from a metal such as Ga, a liquid phase A homocrystal / heteroepitaxially grown single crystal obtained by using an epitaxy method (LPE method), a single crystal produced based on a solution growth method, a crystal obtained by cutting them, and the like can be used. The specific method of epitaxial growth is not particularly limited. For example, a hydride vapor phase growth method (HVPE) method, a metal organic chemical vapor deposition method (MOCVD method), a liquid phase method, an ammonothermal method, or the like is adopted. Can do.

The base substrate used in the present invention is not particularly limited as long as it is a plate-like group 13 nitride seed crystal having a main surface on the front side and a main surface on the back side, but the main surface on the front side and the main surface on the back side are substantially the same. It is preferable that they are parallel. It is more preferable that the main surface on the front side and the main surface on the back side are both M surfaces.
The shape of the seed crystal is not particularly limited, but a large-area growth crystal can be obtained efficiently, so that the outer shape of the main surface is a shape having a longitudinal direction and a short direction such as a rectangle or an ellipse. It is preferable that the straight line extending in the longitudinal direction and the straight line extending in the short direction intersect substantially perpendicularly. The side surface of the seed crystal may be flat or curved. Examples of the shape of the seed crystal include a rectangular parallelepiped, a triangular plate, a pentagonal plate, a hexagonal plate, a disc, a triangular prism, a pentagonal column, a hexagonal column, and a cylinder. Among them, the base substrate used in the present invention is more preferably a plate-shaped rectangular parallelepiped seed crystal.

  The side surface of the seed crystal may be formed by cleaving. For example, when the side surface of the seed crystal is an A plane formed by cleaving, the growth of the growth surface as a semipolar surface is promoted as compared to the case where crystal growth is performed using a seed crystal having an unpolished A surface. And high quality nitride crystals can be produced at a high growth rate. Further, since dislocations generated from the seed crystal interface are reduced as compared with the case of unpolished, the dislocation density in the grown crystal can be further reduced.

  The thickness of the base substrate used in the present invention (when the M surface is the main surface, the dimension in the m-axis direction) is preferably 0.1 mm or more, and more preferably 0.2 mm or more from the viewpoint of handleability. In addition, when the seed crystal is too thick, the ratio of the seed crystal in the grown crystal is increased, leading to an increase in manufacturing cost and cost. Therefore, the thickness of the seed crystal is preferably 2 mm or less, More preferably, it is 1 mm or less.

The base substrate used in the present invention is not limited to the size of the main surface on the front side of the base substrate, but the size in the c-axis direction, which is the longitudinal direction of the main surface on the front side of the base substrate, is 200 mm or less as the seed crystal size. Is preferably 150 mm or less, more preferably 5 mm or more, and even more preferably 10 mm or more. On the other hand, the dimension in the a-axis direction, which is the lateral direction of the main surface on the front side of the base substrate, is preferably 300 mm or less, more preferably 200 mm or less, preferably 10 mm or more, and 15 mm or more. Is more preferable.
Further, in the base substrate used in the present invention, it is preferable that the size of the main surface on the front side and the size of the main surface on the back side are substantially the same, and the preferable range of the size of the main surface on the back side of the base substrate used in the present invention. Is the same as the preferred range of dimensions of the main surface on the front side.

The underlying substrate preferably has an intrinsic number of dislocation density of 1 × 10 ⁸ / cm ² or less from the viewpoint of suppressing the generation of cracks after crystal growth and preventing crystal breakage during growth, and preferably 1 × 10 ⁷ / cm ² or less. More preferably, it is particularly preferably 5 × 10 ⁶ / cm ² or less.
The radius of curvature of the crystal lattice plane of the main surface of the base substrate is preferably 0.5 m or more, more preferably 1 m or more, from the viewpoint of suppressing the generation of cracks after crystal growth and preventing crystal breakage during growth. The above is particularly preferable.

(Growth crystal mass)
As shown in FIG. 4, a group 13 nitride semiconductor crystal can be grown on the base substrate 40 to obtain a group 13 nitride growth crystal lump 100. The main surface 51 of the group 13 nitride crystal block formed on the main surface 41 on the front side of the base substrate 40 is an M-plane.
The growth crystal lump has a group 13 nitride semiconductor crystal (growth crystal) formed on the base substrate. The group 13 nitride semiconductor crystal is obtained by growing a group 13 nitride semiconductor crystal of the same type as the seed crystal. The Group 13 nitride semiconductor crystal is not particularly limited as long as it has a hexagonal crystal structure. For example, the Group 13 nitride constituting the seed crystal and the growth crystal includes gallium nitride, aluminum nitride, Those using indium nitride or a mixed crystal thereof are preferable, and gallium nitride is particularly preferable among them.

  The specific method for growing the grown crystal on the seed crystal is not particularly limited, and vapor phase methods such as hydride vapor phase epitaxy (HVPE), metal organic chemical vapor deposition (MOCVD), and liquid phase epitaxy. Liquid phase methods such as (LPE method), ammonothermal methods and the like can be mentioned, but ammonothermal methods can be preferably employed. The ammonothermal method is particularly preferably an ammonothermal method using a mineralizer containing fluorine element and at least one selected from other halogen elements composed of chlorine, bromine and iodine.

FIG. 5 shows a cross-sectional view of the growth crystal mass of the group 13 nitride shown in FIG. Further, FIG. 6 shows cross-sectional views of examples of various types of grown crystal masses. As can be seen from these cross-sectional views, in the growth crystal lump, the entire surface of the base substrate is covered with the growth crystal, and the growth crystal constitutes the crystal surface of the growth crystal lump.
The group 13 nitride semiconductor substrate according to the present invention can be obtained by slicing, grinding, polishing, or the like the above-described growth crystal mass. For example, as shown in FIG. 6, a group 13 nitride semiconductor substrate can be obtained by slicing along a slice line indicated by a dotted line A.

In the growing crystal mass according to the present invention, the crystal surface preferably includes at least a [10-11] or [10-1-1] plane. The growth crystal mass of the present invention is controlled so that the semipolar plane (Semi-Polar plane) becomes the surface so that the [10-11] or [10-1-1] plane is formed. Growing up. The semipolar plane may be a plane in which a plurality of crystal planes are aggregated.
The growth crystal lump according to the present invention has an M (10-10) plane as a main surface 51 as shown in FIGS. 4 to 6, and a (10-1-1) plane and a (10-11) plane as side surfaces. It is preferable that it grows while at least appearing, has an M surface as a main surface in an as-grown state, and includes at least a (10-1-1) surface and a (10-11) surface as side surfaces. Furthermore, it grows while at least one of the (0001) plane and the (000-1) plane appears, and has at least one of the (0001) plane and the (000-1) plane in the as-grown state. Also good. Preferably, it has a (0001) plane in an as-grown state. This makes it possible to reduce the outer second region obtained by growing using [10-11] as the growth surface.
4 to 6, 53 and 54 are M planes, 61, 63 and 64 are (10-1-1) planes, and 71 to 76 are (10-11) planes.

  In order for the crystal surface of the growing crystal mass to include at least the M plane and the [10-11] or [10-1-1] plane, as a mineralizer described later, at least a fluorine element, chlorine, bromine, It is preferable to use a mineralizer containing at least one selected from other halogen elements composed of iodine. As the mineralizer, those containing elemental fluorine and iodine are particularly preferable. As described above, when a mineral containing a fluorine element and iodine is used as a mineralizer, a crystal lump having at least a [10-11] or [10-1-1] plane and having a large main surface can be easily obtained. .

  When using a mineral element containing elemental fluorine (F) and iodine (I), the iodine concentration relative to the fluorine concentration, that is, the I / F is preferably 0.5 or more, and 0.7 or more. Is more preferable, and it is more preferable to set it to 1 or more. The I / F is preferably 10 or less, more preferably 9 or less, and even more preferably 8 or less.

Moreover, the growth which makes a growth surface a semipolar surface can be promoted by reducing the density | concentration of the impurity in a growth crystal. At this time, the impurity concentration can be based on oxygen concentration, alkali metal, transition metal concentration such as Ni, or the like. For example, by setting the oxygen concentration in the grown crystal to less than 10 ²⁰ atoms / cm ³ , growth with the growth surface as a semipolar surface can be promoted. As a result, the semipolar plane appearing on the surface of the grown crystal lump is narrowed and the M-plane is widened, which is preferable because a high quality region in the group 13 nitride substrate of the present invention can be widened. The oxygen atom concentration when oxygen atoms are contained as impurity atoms in the grown crystal is preferably 1 × 10 ²⁰ atoms / cm ³ or less, more preferably 5 × 10 ¹⁹ atoms / cm ³ or less. × and more preferably 10 ¹⁹ atoms / cm ³ or less.

  Further, the growth of the growth surface as a surface including the M plane and the semipolar plane can be promoted by appropriately selecting the shape of the seed crystal, the processing method, and the like.

(Crystal growth by ammonothermal method)
Periodic group 13 metal nitride crystals on the periodic group 13 metal nitride semiconductor substrate are formed by an ammonothermal method. The ammonothermal method is a method for producing a desired material by using a dissolution-precipitation reaction of raw materials using a solvent containing nitrogen such as ammonia in a supercritical state and / or a subcritical state.
The mineralizer, solvent, and raw material which can be used for the crystal growth method in the present invention are described below.

(Mineralizer)
In the growth of nitride crystals by the ammonothermal method in the present invention, a mineralizer is preferably used. Since the solubility of the crystal raw material in a solvent containing nitrogen such as ammonia is not high, a mineralizer is used to improve the solubility.
As the mineralizer, a mineralizer containing at least one element selected from fluorine element and other halogen elements composed of chlorine, bromine and iodine is preferably used.

The combination of halogen elements contained in the mineralizer may be a combination of two elements such as chlorine and fluorine, bromine and fluorine, iodine and fluorine, chlorine and bromine and fluorine, chlorine and iodine and fluorine, bromine and iodine. It may be a combination of three elements such as fluorine and fluorine, or a combination of four elements such as chlorine, bromine, iodine and fluorine. Preferred is a combination containing at least iodine and fluorine from the viewpoint of controlling the surface expressed in the a-axis direction to a semipolar surface as described above. The combination and concentration ratio (molar concentration ratio) of the halogen elements contained in the mineralizer used in the present invention are the type, shape and size of the nitride crystal to be grown, and the type, shape and size of the seed crystal used. It can be appropriately determined depending on the reaction apparatus, the temperature conditions and pressure conditions employed, and the like.
For example, in the case of a mineralizer containing iodine (I) and fluorine (F), the iodine concentration relative to the fluorine concentration, that is, the I / F is preferably 0.5 or more, more preferably 0.7 or more. More preferably, it is 1 or more. The I / F is preferably 10 or less, more preferably 8 or less, and even more preferably 5 or less.

  Generally, when the fluorine concentration of the mineralizer is increased, the growth rate of the nitride crystal in the m-axis direction tends to increase, and the growth in the c-axis direction and the growth perpendicular to the semipolar plane tend to be relatively slow. It is in. This means that the difference in growth rate depending on the plane orientation can be controlled by changing the mineralizer concentration. Thereby, the appearance area of the plane orientation with a high growth rate is narrowed, and the appearance area of the plane orientation with a relatively low growth rate can be controlled to be widened. In the group 13 nitride substrate of the present invention, This is preferable because a high quality area can be widened.

  Examples of mineralizers containing halogen elements include ammonium halide, hydrogen halide, ammonium hexahalosilicate, and hydrocarbyl ammonium fluoride, tetramethyl ammonium halide, tetraethyl ammonium halide, benzyl trimethyl ammonium halide, halogen Examples thereof include alkylammonium salts such as dipropylammonium halide and isopropylammonium halide, alkyl metal halides such as sodium alkyl fluoride, alkaline earth metal halides and metal halides. Of these, preferred are alkali halides, alkaline earth metal halides, metal halides, ammonium halides, and hydrogen halides, and more preferred are alkali halides, ammonium halides, and halogens of Group 13 metals of the periodic table. A halide and a hydrogen halide, particularly preferably an ammonium halide, a gallium halide and a hydrogen halide.

In the production process, a mineralizer containing no halogen element can be used together with a mineralizer containing a halogen element. For example, it can be used in combination with an alkali metal amide such as NaNH ₂ , KNH _2, or LiNH _2. it can. When a halogen element-containing mineralizer such as ammonium halide and a mineralizer containing an alkali metal element or alkaline earth metal element are used in combination, it is preferable to increase the amount of the halogen element-containing mineralizer. Specifically, the mineralizer containing an alkali metal element or alkaline earth metal element is preferably 50 to 0.01 parts by mass with respect to 100 parts by mass of the halogen element-containing mineralizer. It is more preferable to set it as 1 mass part, and it is further more preferable to set it as 5-0.2 mass part. By adding a mineralizer containing an alkali metal element or alkaline earth metal element, the ratio of the m-axis crystal growth rate to the crystal growth rate in the c-axis direction (m-axis / c-axis) can be further increased. It is.

  In addition to changing the concentration of the mineralizer, the growth rate can be changed by the dopant. In the manufacturing process, the mineralizer can be used after being purified and dried as necessary in order to prevent impurities from being mixed into the nitride crystal to be grown. The purity of the mineralizer is usually 95% or higher, preferably 99% or higher, more preferably 99.99% or higher.

  It is desirable that the amount of water and oxygen contained in the mineralizer is as small as possible, and the content thereof is preferably 1000 ppm or less, more preferably 10 ppm or less, and further preferably 1.0 ppm or less. . By controlling the oxygen concentration within these ranges, the higher the oxygen concentration, the lower the growth rate in the direction perpendicular to the semipolar plane, that is, the area of the semipolar plane tends to increase. On the other hand, the lower the oxygen concentration, the higher the growth rate in the direction perpendicular to the semipolar plane, that is, the area of the semipolar plane tends to decrease.

  When crystal growth is performed, aluminum halide, phosphorus halide, silicon halide, germanium halide, zinc halide, arsenic halide, tin halide, antimony halide, bismuth halide, etc. are added to the reaction vessel. It may be present.

  The molar concentration of the halogen element contained in the mineralizer with respect to the solvent is preferably 0.1 mol% or more, more preferably 0.3 mol% or more, and further preferably 0.5 mol% or more. The molar concentration of the halogen element contained in the mineralizer is preferably 30 mol% or less, more preferably 20 mol% or less, and even more preferably 10 mol% or less. If the concentration is too low, the solubility tends to decrease and the growth rate tends to decrease. On the other hand, when the concentration is too high, there is a tendency that the solubility becomes too high and the generation of spontaneous nuclei increases, or the control becomes difficult because the supersaturation degree becomes too high.

(solvent)
As a solvent used in the ammonothermal method, a solvent containing nitrogen can be used. Examples of the solvent containing nitrogen include a solvent that does not impair the stability of the grown nitride single crystal. Examples of the solvent include ammonia, hydrazine, urea, amines (for example, primary amines such as methylamine, secondary amines such as dimethylamine, tertiary amines such as trimethylamine, and ethylenediamine. Diamine) and melamine. These solvents may be used alone or in combination.

  The amount of water and oxygen contained in the solvent is desirably as small as possible, and the content thereof is preferably 1000 ppm or less, more preferably 10 ppm or less, and further preferably 0.1 ppm or less. When ammonia is used as a solvent, the purity is usually 99.9% or more, preferably 99.99% or more, more preferably 99.999% or more, and particularly preferably 99.9999% or more. .

(material)
In the manufacturing process, a raw material containing an element constituting a nitride crystal to be grown as a growth crystal on a seed crystal is used. For example, when a nitride crystal of a periodic table 13 group metal is to be grown, a raw material containing a periodic table 13 group metal is used. Preferred is a polycrystalline raw material of a group 13 nitride crystal and / or a group 13 metal, and more preferred is gallium nitride and / or metal gallium. The polycrystalline raw material does not need to be a complete nitride, and may contain a metal component in which the group 13 element is in a metal state (zero valence) depending on conditions. For example, when the crystal is gallium nitride Is a mixture of gallium nitride and metal gallium.

  The method for producing the polycrystalline raw material is not particularly limited. For example, a nitride polycrystal produced by reacting a metal or an oxide or hydroxide thereof with ammonia in a reaction vessel in which ammonia gas is circulated can be used. In addition, as a metal compound raw material having higher reactivity, a compound having a covalent MN bond such as a halide, an amide compound, an imide compound, or galazan can be used. Furthermore, a nitride polycrystal produced by reacting a metal such as Ga with nitrogen at a high temperature and a high pressure can also be used.

  The amount of water and oxygen contained in the polycrystalline raw material used as the raw material in the present invention is preferably small. The oxygen content in the polycrystalline raw material is usually 10,000 ppm or less, preferably 1000 ppm or less, particularly preferably 1 ppm or less. The ease of mixing oxygen into the polycrystalline raw material is related to the reactivity with water or the absorption capacity. The worse the crystallinity of the polycrystalline raw material, the more active groups such as NH groups exist on the surface, which may react with water and partially generate oxides or hydroxides. For this reason, it is usually preferable to use a polycrystalline material having as high crystallinity as possible. The crystallinity can be estimated by the half width of powder X-ray diffraction. The half width of the (100) diffraction line (2θ = about 32.5 ° for hexagonal gallium nitride) is usually 0.25 ° or less, preferably It is 0.20 ° or less, more preferably 0.17 ° or less.

(manufacturing device)
A specific example of a crystal manufacturing apparatus that can be used in the nitride crystal manufacturing method of the present invention is shown in FIG. The crystal production apparatus used in the present invention includes a reaction vessel. FIG. 7 is a schematic view of a crystal manufacturing apparatus that can be used in the present invention. In the crystal manufacturing apparatus shown in FIG. 7, crystal growth is performed in a capsule (inner cylinder) 20 loaded as a reaction vessel in the autoclave 1 (pressure resistant vessel). The capsule 20 includes a raw material filling region 9 for dissolving the raw material and a crystal growth region 6 for growing crystals. In the raw material filling area 9, a solvent and a mineralizer can be put together with the raw material 8. A seed crystal 7 can be installed in the crystal growth region 6 by suspending it with a wire 4. Between the raw material filling region 9 and the crystal growth region 6, a partition baffle plate 5 is installed in two regions. The baffle plate 5 has a hole area ratio of preferably 2 to 60%, more preferably 3 to 40%. The material of the surface of the baffle plate is preferably the same as the material of the capsule 20 that is a reaction vessel. Further, in order to give more corrosion resistance and to purify the crystal to be grown, the surface of the baffle plate is Ni, Ta, Ti, W, Mo, Ru, Nb, Pd, Pt, Au, Ir, pBN. Of these, W, Mo, Ti, Pd, Pt, Au, Ir, and pBN are more preferable, and Pt, Mo, and Ti are particularly preferable.
In the crystal manufacturing apparatus shown in FIG. 7, the space between the inner wall of the autoclave 1 and the capsule 20 can be filled with the second solvent. Here, ammonia can be filled as the second solvent while filling the nitrogen gas from the nitrogen cylinder 13 through the valve 10 or confirming the flow rate from the ammonia cylinder 12 with the mass flow meter 14. In addition, the vacuum pump 11 can perform necessary pressure reduction. Note that a valve, a mass flow meter and the like are not necessarily installed in the crystal manufacturing apparatus used when the nitride crystal manufacturing method of the present invention is carried out.

  Lining can also be used to provide corrosion resistance by autoclaving. The lining material is preferably at least one metal or element of Pt, Ir, Ag, Pd, Rh, Cu, Au and C, or an alloy or compound containing at least one metal, More preferably, it is an alloy or compound containing at least one or more metals or elements of Pt, Ag, Cu and C, or at least one or more metals because they are easily lined. For example, Pt simple substance, Pt-Ir alloy, Ag simple substance, Cu simple substance, graphite, etc. are mentioned.

(Manufacturing process)
An example of the method for producing a nitride crystal of the present invention will be described. In carrying out the method for producing a nitride crystal of the present invention, first, a seed crystal, a nitrogen-containing solvent, a raw material, and a mineralizer are put in a reaction vessel and sealed. Here, as the seed crystal, a nitride crystal grown with the C-plane as the main surface is cut out in a desired direction, whereby a substrate whose main surface is a nonpolar surface or a semipolar surface can be obtained. Thereby, a seed crystal having a nonpolar plane such as an M plane and a semipolar plane such as (10-11) or (20-21) can be obtained.

  In the production process of the present invention, a dopant source isolation step may be further provided prior to introducing the material into the reaction vessel. The dopant source isolation step refers to a step of removing oxygen, oxide or water vapor present in the reaction vessel. The dopant source isolation step includes a step of coating or lining the surface of a reaction vessel or a member containing oxygen, oxide, or water vapor among various members installed in the reaction vessel. Coating or lining the surface of the member can prevent the dopant from being exposed and incorporated into the nitride crystal.

  In order to remove oxygen, oxides or water vapor present in the reaction vessel, the reaction vessel is filled with a nitride crystal raw material, and then the reaction vessel is evacuated, or an inert gas is contained in the reaction vessel. A method that satisfies the above can be adopted. In addition, oxygen, oxides, or water vapor can be removed by drying the reaction vessel and various members included in the reaction vessel.

At the time of introducing the material, an inert gas such as nitrogen gas may be circulated. Usually, the seed crystal is placed in the reaction vessel at the same time or after filling the raw material and the mineralizer. The seed crystal is preferably fixed to a noble metal jig similar to the noble metal constituting the inner surface of the reaction vessel. After installation of the seed crystal, heat deaeration may be performed as necessary.
When the production apparatus shown in FIG. 7 is used, the capsule 20 is sealed in the capsule 20 which is a reaction vessel by putting the seed crystal 7, a nitrogen-containing solvent, a raw material, and a mineralizer, and then sealing the capsule 20 with an autoclave (pressure resistance). Container) 1, and preferably, the space between the pressure-resistant container and the reaction container is filled with the second solvent to seal the pressure-resistant container.

  Thereafter, the whole is heated to bring the inside of the reaction vessel into a supercritical state or a subcritical state. In the supercritical state, the viscosity of a substance is generally low and it diffuses more easily than a liquid, but has a solvating power similar to that of a liquid. The subcritical state means a liquid state having a density substantially equal to the critical density near the critical temperature. For example, in the raw material filling part, the raw material is melted in a supercritical state, and in the crystal growth part, the temperature is changed so that it becomes a subcritical state, and crystal growth using the difference in solubility between the supercritical state and the subcritical state of the raw material Is possible.

  In the supercritical state, the reaction mixture is generally maintained at a temperature above the critical point of the solvent. When an ammonia solvent is used, the critical point is a critical temperature of 132 ° C. and a critical pressure of 11.35 MPa. However, if the filling rate with respect to the volume of the reaction vessel is high, the pressure far exceeds the critical pressure even at a temperature below the critical temperature. In the present invention, the “supercritical state” includes such a state exceeding the critical pressure. Since the reaction mixture is enclosed in a constant volume reaction vessel, the increase in temperature increases the pressure of the fluid. In general, if T> Tc (critical temperature of one solvent) and P> Pc (critical pressure of one solvent), the fluid is in a supercritical state.

  Under supercritical conditions, a sufficient growth rate of nitride crystals can be obtained. The reaction time depends in particular on the reactivity of the mineralizer and the thermodynamic parameters, ie temperature and pressure values. During the synthesis or growth of the nitride crystal, the pressure in the reaction vessel is preferably 30 MPa or more, more preferably 60 MPa or more, and further preferably 100 MPa or more, from the viewpoint of crystallinity and productivity. . The pressure in the reaction vessel is preferably 700 MPa or less, more preferably 500 MPa or less, further preferably 350 MPa or less, and particularly preferably 300 MPa or less from the viewpoint of safety. The pressure is appropriately determined depending on the filling rate of the solvent volume with respect to the temperature and the volume of the reaction vessel. Originally, the pressure in the reaction vessel is uniquely determined by the temperature and the filling rate, but in practice, the raw materials, additives such as mineralizers, temperature heterogeneity in the reaction vessel, and free volume Depending on the presence of

From the viewpoint of crystallinity and productivity, the lower limit of the temperature range in the reaction vessel is preferably 320 ° C or higher, more preferably 370 ° C or higher, and further preferably 450 ° C or higher. From the viewpoint of safety, the upper limit value is preferably 700 ° C. or less, more preferably 650 ° C. or less, and further preferably 630 ° C. or less. In the method for producing a nitride crystal of the present invention, the temperature of the raw material filling region in the reaction vessel is preferably higher than the temperature of the crystal growth region. The temperature difference (| ΔT |) is preferably 5 ° C. or more, more preferably 10 ° C. or more, from the viewpoint of crystallinity and productivity, and 100 ° C.
Or less, more preferably 90 ° C. or less, and particularly preferably 80 ° C. or less. The optimum temperature and pressure in the reaction vessel can be appropriately determined depending on the type and amount of mineralizer and additive used during crystal growth.

  In order to achieve the temperature range and pressure range in the reaction vessel, the injection rate of the solvent into the reaction vessel, that is, the filling rate, is the free volume of the reaction vessel, that is, when crystal raw materials and seed crystals are used in the reaction vessel. Subtract the volume of the seed crystal and the structure on which the seed crystal is installed from the volume of the reaction vessel, and if a baffle plate is installed, subtract the volume of the baffle plate from the volume of the reaction vessel to remain. Based on the liquid density at the boiling point of the solvent of volume, it is usually 20 to 95%, preferably 30 to 80%, more preferably 40 to 70%. When the capsule 20 as shown in FIG. 7 is used as the reaction vessel, it is preferable to appropriately adjust the amount of the solvent so that the pressure is balanced inside and outside the capsule 20 in the supercritical state of the solvent.

Nitride crystal growth in the reaction vessel is maintained in a subcritical or supercritical state of a solvent such as ammonia by heating and heating the reaction vessel using an electric furnace with a thermocouple. Is done. The heating method and the rate of temperature increase to a predetermined reaction temperature are not particularly limited, but are usually performed over several hours to several days. If necessary, the temperature can be raised in multiple stages, or the temperature raising speed can be changed in the temperature range. It can also be heated while being partially cooled.
The above-mentioned “reaction temperature” is measured by a thermocouple provided so as to be in contact with the outer surface of the reaction vessel and / or a thermocouple inserted into a hole having a certain depth from the outer surface, and It can be estimated in terms of internal temperature. The average value of the temperatures measured with these thermocouples is taken as the average temperature. Usually, an average value of the temperature of the raw material filling region and the temperature of the crystal growth region is defined as the average temperature.

  In the method for producing a nitride crystal of the present invention, a pretreatment can be added to the seed crystal. Examples of the pretreatment include subjecting the seed crystal to a meltback process, polishing the growth surface of the seed crystal, and washing the seed crystal.

  In the pretreatment, in order to polish the surface of the seed crystal capable of crystal growth, for example, chemical mechanical polishing (CMP) can be performed. As for the surface roughness of the seed crystal, for example, the root mean square roughness (Rms) measured by an atomic force microscope is preferably 1.0 nm or less, more preferably 0.5 nm, and particularly preferably 0.3 nm. .

  The reaction time after reaching a predetermined temperature varies depending on the type of nitride crystal, the raw material used, the type of mineralizer, and the size and amount of the crystal to be produced, but is usually several hours to several hundred days. be able to. During the reaction, the reaction temperature may be constant, or the temperature may be gradually raised or lowered. After a reaction time for forming the desired crystal, the reaction temperature is lowered. The temperature lowering method is not particularly limited, but the heating may be stopped while the heating of the heater is stopped and the reaction vessel is installed in the furnace as it is, or the reaction vessel may be removed from the electric furnace and air cooled. If necessary, quenching with a refrigerant is also preferably used.

  After the temperature of the outer surface of the reaction vessel or the estimated temperature inside the reaction vessel is below a predetermined temperature, the reaction vessel is opened. The predetermined temperature at this time is not particularly limited, and is usually −80 ° C. to 200 ° C., preferably −33 ° C. to 100 ° C. Here, the valve may be opened by pipe connection to a valve connection port of the valve attached to the reaction vessel, passing through a vessel filled with water or the like. Furthermore, if necessary, remove the ammonia solvent in the reaction vessel sufficiently by applying a vacuum, etc., then dry, open the reaction vessel lid, etc., and generate nitride crystals and unreacted raw materials and mineralization. Additives such as agents can be removed.

  In addition, when manufacturing gallium nitride according to the method for manufacturing a nitride crystal of the present invention, JP 2009-263229 A can be preferably referred to for details of materials, manufacturing conditions, manufacturing apparatuses, and processes other than those described above. . The entire disclosure of this publication is incorporated herein by reference.

  In the method for producing a nitride crystal of the present invention, after the nitride crystal is grown on the seed crystal, post-treatment may be added. The type and purpose of post-processing are not particularly limited. For example, the crystal surface may be melted back in the cooling process after growth so that crystal defects such as pits and dislocations can be easily observed.

(Epitaxial wafer)
The epitaxial wafer has a semiconductor multilayer structure including a Group 13 nitride semiconductor substrate and an epitaxially grown film provided on the substrate. The group 13 nitride semiconductor substrate according to the present invention can be preferably used as a base substrate because the substrate area is large. An epitaxial wafer can be obtained by using the group 13 nitride semiconductor substrate according to the present invention as a base substrate and growing an epitaxial growth film thereon. The epitaxial growth film is preferably a crystal of the same kind as that of the group 13 nitride semiconductor substrate. For example, when the group 13 nitride semiconductor substrate is a GaN substrate, the epitaxial growth film is also preferably a GaN crystal.

  Since the group 13 nitride semiconductor substrate according to the present invention has a large area with the M-plane as the main surface, the epitaxial growth film can be efficiently grown on the M-plane. Moreover, the size of the obtained epitaxial wafer can also be made large.

(device)
The epitaxial wafer obtained by the production method of the present invention is suitably used for devices such as light emitting elements, electronic devices, and power devices. Examples of the light-emitting element in which the nitride crystal or wafer of the present invention is used include a light-emitting diode, a laser diode, and a light-emitting element that combines them with a phosphor. In addition, examples of the electronic device using the nitride crystal or wafer of the present invention include a high frequency element, a high withstand voltage high output element, and the like. Examples of high-frequency elements include transistors (HEMT, HBT), and examples of high-voltage high-power elements include thyristors (SCR, GTO), insulated gate bipolar transistors (IGBT), and Schottky barrier diodes (SBD). . Since the epitaxial wafer of the present invention has a feature of excellent pressure resistance, it is suitable for any of the above applications.

  The features of the present invention will be described more specifically with reference to examples and comparative examples. The materials, amounts used, ratios, processing details, processing procedures, and the like shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be construed as being limited by the specific examples shown below.

Example 1
In this example, a nitride crystal was grown using the reactor shown in FIG.
Crystal growth was carried out using an autoclave 1 having an inner diameter of 30 mm and a length of 450 mm as a pressure-resistant container and a Pt-Ir capsule 20 as a reaction container. As the raw material 8, 130 g of polycrystalline GaN particles were weighed and placed in the capsule lower region (raw material filling region 9). Next, NH ₄ F having a purity of 99.999% sufficiently dried as a mineralizer was weighed so that the F concentration was 0.5 mol% with respect to the amount of NH ₃ charged, and charged into the capsule. Further, a platinum baffle plate 5 (opening ratio: 32%) was placed between the lower raw material dissolution region 9 and the upper crystal growth region 6. As the seed crystal 7, a plate-shaped hexagonal GaN single crystal having an M-plane as a main surface and a main surface being a quadrangle was used. The surface of the seed crystal having the M plane as the principal plane was subjected to CMP finish. These seed crystals 7 were hung on a platinum seed crystal support frame by a platinum wire and placed in the crystal growth region 6 above the capsule.

  Next, after a cap made of Pt—Ir was connected to the upper part of the capsule 20 by welding, the tube was connected to the HI gas line, and the valve was operated so as to communicate with the vacuum pump 11 to perform vacuum deaeration. Thereafter, the valve was operated so as to pass through the nitrogen cylinder 13 and the inside of the capsule was purged with nitrogen gas. After performing vacuum degassing and nitrogen purging, it was left overnight while connected to a vacuum pump. The ultimate vacuum at this time was 0.8 Pa.

Next, the lower part of the capsule was cooled with liquid nitrogen, and the valve was opened and filled with HI without touching the outside air. Based on the flow rate control, HI was charged so that the I concentration was 1.5 mol% with respect to the amount of NH ₃ charged, and then the valve was closed again. Next, the capsule was removed from the HI line and connected to an NH ₃ gas line. After the gas line was vacuum degassed, vacuuming was performed with a vacuum pump. Thereafter, the valve of the NH ₃ line was operated, and based on the flow rate control, an equimolar amount of HI gas previously filled with NH ₃ was filled, and the valve was closed. The capsules were then removed from the liquid nitrogen and cooled with dry ice ethanol solvent. Subsequently, the valve was opened again and charged with NH ₃ without touching the outside air, and then the valve was closed again. Thereafter, the tube at the top of the cap was sealed with a welder.

Subsequently, the capsule was inserted into the autoclave and the autoclave was sealed. The conduit was connected to the vacuum pump 11 through the valve 10 attached to the autoclave, and the valve was opened to perform vacuum deaeration. Nitrogen gas purging was performed several times as in the capsule. Thereafter, the autoclave 1 was cooled with a dry ice methanol solvent while maintaining the vacuum state, and the valve 10 was once closed. Next, after the conduit was operated to lead to the NH ₃ cylinder 12, the valve 10 was opened again, and NH ₃ was filled in the autoclave 1 without continuously touching the outside air, and then the valve 10 was closed again.

  Subsequently, the autoclave 1 was housed in an electric furnace composed of a heater divided into two parts in the vertical direction. The temperature was raised while controlling the external temperature of the autoclave so that the average temperature inside the autoclave was 600 ° C. and the internal temperature difference was 20 ° C. After reaching the set temperature, the temperature was maintained at that temperature for 14.8 days. The pressure in the autoclave was 215 MPa. Further, the variation in the control temperature of the outer surface of the autoclave during the holding was ± 0.3 ° C. or less.

Thereafter, the temperature of the outer surface of the autoclave 1 was cooled to 400 ° C., the valve 10 attached to the autoclave was opened, and NH ₃ in the autoclave was removed. At this time, the capsule was divided using the pressure difference between the autoclave and the capsule, and NH ₃ filled in the capsule was also removed.

Thereafter, the lid of the autoclave was opened and the capsule 20 was taken out. When the inside of the capsule was confirmed, a gallium nitride crystal was grown on the seed crystal. In the crystal, the M plane, the (10-11) plane, the (10-1-1) plane, and the + C plane form facets, the M plane is colored pale yellow, and the S plane is colored brown. Observed. The growth rate ratio of the M face to the S face from the crystal outer diameter was 0.88. A GaN substrate obtained by slicing the obtained crystal so that the M-plane becomes the main surface at 22% of the growth thickness on one side from the surface of the M-plane contained 12.7% of the outer region. (Example 1-A). The outer region in the GaN substrate sliced at a position 45% from the surface was 19.8% (Example 1-B), and the outer region in the GaN substrate sliced at 68% was 20.9% (Example 1). -C), the outer region in the GaN substrate sliced at 90% was 21.5% (Example 1-D). Each has an outer first region grown with the (10-1-1) plane as the growth plane and an outer second region grown with the (10-11) plane as the growth plane across the central region. The area of one region was larger.
As a result of analyzing the impurity concentration in the outer first region, the outer second region, and the central region by SIMS analysis, the oxygen concentration in the outer first region, the outer second region, and the central region is 2.88 × 10 ¹⁸ atms / cm ^{3, respectively.} (Outer first region), 6.07 × 10 ¹⁸ atms / cm ³ (outer second region), 3.63 × 10 ¹⁸ atms / cm ³ (center region). Similarly, the fluorine concentration is 2.53 × 10 ¹⁷ atms / cm ³ (outer first region), 1.83 × 10 ¹⁷ atms / cm ³ (outer second region), 1.48 × 10 ¹⁷ atms / cm ^3. (Central area).

(Example 2)
In the same procedure as in Example 1, the crystal was grown with the ultimate vacuum in the capsule of 3.0 Pa. In the grown crystal, the M plane, the (10-11) plane, the (10-1-1) plane, and the + C plane form facets, the M plane is colored pale yellow, and the S plane is colored brown. Was observed. The growth rate ratio of the M face to the S face from the crystal outer diameter was 0.91. 30% of the outer region was contained in the GaN substrate obtained by slicing the obtained crystal so that the M plane became the main surface at 22% of the growth thickness on one side from the surface of the M plane (Example) 2-A). Further, the outer region in the GaN substrate sliced at a position 45% from the surface is 46.7% (Example 2-B), and the outer region in the GaN substrate sliced at 68% is 52% (Example 2-C). ), The outer region in the GaN substrate sliced at 90% was 54.7% (Example 2-C). Each has an outer first region grown using the (10-1-1) plane as a growth surface and an outer second region grown using the (10-11) plane as a growth surface, and the area of the outer first region is It was bigger.

(Example 3)
In the same procedure as in Example 1, the crystal growth was performed with the mineralizer concentration ratio I / F being 1.47 and the ultimate vacuum in the capsule being 20 Pa. The grown crystal had a narrow M-plane and a wide (10-1-1) plane. Further, the (10-11) plane and the + C plane formed facets. The M surface was colored light yellow, and the S surface was observed to be brown. The growth rate ratio of the M face to the S face from the crystal outer diameter was 0.93. In the GaN substrate obtained by slicing the obtained crystal so that the M-plane becomes the main surface at 23.8% of the growth thickness on one side from the surface of the M-plane, the outer region contains 32.3%. (Example 3-A). The outer region in the GaN substrate sliced at 47.6% from the surface was 33.3% (Example 3-B), and the outer region in the GaN substrate sliced at 71.4% was 33% (implemented). Example 3-C). Each has an outer first region grown with the (10-1-1) plane as the growth plane and an outer second region grown with the (10-11) plane as the growth plane across the central region. The area of one region was larger.

Example 4
Crystal growth was carried out in the same procedure as in Example 1, with the mineralizer concentration ratio I / F set to 3 and the ultimate vacuum in the capsule set to 5.27 × 10 ⁻² Pa. In the crystal, the M plane, the (10-1-1) plane, and the + C plane formed facets, and the (10-11) plane was not observed. The M surface was colored light yellow, and the S surface was observed to be brown. The growth rate ratio of the M face to the S face from the crystal outer diameter was 0.94. In the GaN substrate obtained by slicing the obtained crystal so that the M-plane becomes the main surface at 30% of the growth thickness on one side from the surface of the M-plane, 9.9% of the outer region was included ( Example 4-A). Further, the outer region in the GaN substrate sliced at a position of 60% from the surface was 13.8% (Example 4-B).

  As described above, in Examples 1 to 4, by having the outer region, a semiconductor substrate having a size sufficient for device processing can be obtained, and a high-quality and uniform crystal region is formed in the central portion of the semiconductor substrate. A semiconductor substrate having the same can be obtained. Thus, it has been found that the size of the semiconductor substrate having the M plane as the main surface can be increased in the present invention.

  ADVANTAGE OF THE INVENTION According to this invention, it is a semiconductor substrate which has M surface as a main surface, Comprising: A semiconductor substrate with a large substrate area can be provided. In addition, the manufacturing cost per unit area of the semiconductor substrate can be suppressed. For this reason, this invention is useful for various devices, such as a power device, and its industrial applicability is high.

1 Autoclave (pressure-resistant container)
4 Wire 5 Baffle plate 6 Crystal growth area 7 Seed crystal 8 Raw material 9 Raw material filling area 10 Valve 11 Vacuum pump 12 Ammonia cylinder 13 Nitrogen cylinder 14 Mass flow meter 20 Capsule (inner cylinder)
40 Underlying substrate (seed crystal)
41 M-plane of base substrate 51 M-plane of growth crystal lump 61 S-plane of growth crystal lump: [10-1-1] plane 71 S-plane of growth crystal lump: [10-11] plane 81 C-plane of growth crystal lump : [0001] face 53 to 54 M face included in side face of group 13 nitride crystal lump 63 to 64 included in side face of group 13 nitride crystal lump, on main face of crystal lump on −c axis side Non-contact (10-1-1) plane 71-72 (10-11) plane 73-76 Group 13 included in the side surface of the Group 13 nitride crystal block and in contact with the main surface of the Group 13 nitride crystal block (10-11) plane that is included in the side surface of the nitride crystal lump and does not contact the main surface of the group 13 nitride crystal lump on the + c axis side 100 Growing crystal lump A Slice line M Central region S Outer region S1 Outer 1 area S2 outside 2nd area

Claims (15)

A periodic table group 13 metal nitride semiconductor substrate having an outer region and a central region adjacent to the outer region, the main surface of which is an M-plane;
The central region is composed of a periodic table group 13 metal nitride crystal grown in the m-axis direction,
The outer region is composed of a periodic table group 13 metal nitride crystal grown in a direction inclined at an angle of 10 ° to 80 ° from the m-axis to the c-axis direction. substrate. The periodic table group 13 metal nitride semiconductor substrate according to claim 1, wherein the main surface has an off-angle in the c-axis direction. The ratio of the area occupied by the outer area and have contact to the main surface is 4 0% or less, the periodic table Group 13 metal nitride semiconductor substrate according to claim 1 or 2. The chromaticity and the chromaticity of the pre-Symbol central region of the outer region are different, periodic table Group 13 metal nitride semiconductor substrate according to any one of claims 1-3. Wherein the outer region comprises fluorine in a concentration of 1 × 10 ¹⁶ atoms / cm ³ or more, the periodic table Group 13 metal nitride semiconductor substrate according to any one of claims 1-4. The low fluoride Motoko degree in the central region than hydrofluoric Motoko degree in the outer region, the periodic table Group 13 metal nitride semiconductor substrate according to claim 5. 7. The outer region includes a region made of a periodic table group 13 metal nitride crystal grown in a direction inclined at an angle of 10 ° to 80 ° in the −c-axis direction from the m-axis. 12. A periodic table group 13 metal nitride semiconductor substrate according to item 1. 8. The periodic table group 13 metal nitride semiconductor substrate according to claim 7, wherein the outer region includes a region made of a periodic table group 13 metal nitride crystal grown using a {10-1-1} plane as a growth surface. 9. . 9. The periodic table group 13 metal nitride semiconductor substrate according to claim 8, wherein the outer region includes a region made of a periodic table group 13 metal nitride crystal grown using a {10-11} plane as a growth surface. It said outer region and an outer first region and the outer-side second region, the central region is the outer first region and a region in which the sandwiched outside the second region, claim 1-9 12. A periodic table group 13 metal nitride semiconductor substrate according to item 1 . The outer first region is composed of a periodic table group 13 metal nitride crystal grown using the { 10-1-1 } plane as a growth surface, and the outer second region is grown using the { 10-11 } plane as a growth surface. made from the periodic table group 13 metal nitride crystal, the area of the outer first region have you on the main surface is greater than the area of the outer second region, periodic table group 13 metal nitride as claimed in claim 10 Semiconductor substrate. The periodic table group 13 metal nitride semiconductor substrate according to claim 1, which is a GaN substrate. Epitaxial wafer comprising a periodic table Group 13 metal nitride semiconductor substrate and the epitaxial growth film according to any one of claims 1 to 12. The manufacturing method of an epitaxial wafer including making a periodic table group 13 metal nitride semiconductor substrate of any one of Claims 1-12 a base substrate, and making an epitaxial growth film grow on it. A device manufacturing method comprising a step of obtaining an epitaxial wafer by growing an epitaxial growth film on the periodic table group 13 metal nitride semiconductor substrate according to any one of claims 1 to 12 as a base substrate. .

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