JP5751182B2 - Nitride crystal manufacturing method, reaction vessel and crystal manufacturing apparatus - Google Patents

Description

  The present invention relates to a method for producing a nitride crystal, and more particularly to a method for producing a nitride crystal using a reaction vessel having a pressure adjustment region. The present invention also relates to a reaction vessel and a crystal production apparatus used in carrying out the production method.

The ammonothermal method is a method for producing a desired material by using a raw material dissolution-precipitation reaction 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. A hydrothermal method similar to the ammonothermal method uses supercritical and / or subcritical water as a solvent for crystal growth, but mainly oxide crystals such as quartz (SiO ₂ ) and zinc oxide (ZnO). It is a method applied to On the other hand, the ammonothermal method can be applied to a nitride crystal and is used for growing a nitride crystal such as gallium nitride.

As a crystal production apparatus used in the ammonothermal method, for example, as disclosed in Patent Documents 1 and 2, the target is placed on the seed crystal in the reaction vessel with the reaction vessel loaded in the pressure-resistant vessel. What precipitates a single crystal is known.
In the ammonothermal method, in order to perform crystal growth, the temperature is increased and the pressure is increased until a solvent such as ammonia in the reaction vessel reaches a supercritical or subcritical state. Here, when using an inner cylinder type reaction vessel as described in Patent Documents 1 and 2, it is necessary to adjust the pressure so that the pressure is approximately equal between the inside of the reaction vessel and the outside of the reaction vessel. There is. This is because, if the pressure inside and outside the reaction vessel is different, the reaction vessel is likely to be crushed or ruptured and damaged.

The following is disclosed about the method of adjusting so that a pressure may become substantially equal between the inside of a reaction container, and the outer side of a reaction container.
Patent Document 2 describes the use of a reaction vessel formed of a material whose entire outer wall surface is deformable as a means for preventing the reaction vessel from bursting due to an increase in the internal pressure of the reaction vessel. . This is to prevent the reaction container from expanding and rupturing when the internal pressure of the reaction container increases (Patent Document 2).
On the other hand, although it is not an ammonothermal method, a method for adjusting the pressure inside and outside the reaction vessel when zinc oxide single crystals are grown by a hydrothermal synthesis method is disclosed in which the reaction vessel has a bellows as a pressure adjusting unit. (Patent Documents 3 and 4).

JP 2009-263229 A JP-T-2006-514581 JP 2003-63889 A JP 2010-53017 A

  In the conventional ammonothermal method using an inner cylindrical container, adjustment for maintaining the pressure balance inside and outside the reaction container is extremely difficult and difficult to actually operate. Also, even if the pressure balance is maintained during crystal growth, if the reaction vessel breaks in the process of taking out the crystal, it cannot be used repeatedly, or if the reaction vessel is crushed, the grown crystal is damaged. There was also a problem that the crystal could not be taken out.

  In the study of the present inventors, the ammonothermal method has found that the pressure outside the reaction vessel tends to increase, and as a result, the pressure balance inside and outside the reaction vessel tends to be lost. In particular, in the process where the temperature changes, such as when the inside of the pressure-resistant vessel is cooled after the crystal growth is completed, it has been found that the pressure balance tends to be lost and it is difficult to make this adjustment. This problem relates to a pressure increase outside the reaction vessel, and cannot be solved by the invention described in Patent Document 2.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have used a reaction vessel provided with a pressure adjustment region in a part of the reaction vessel, so that a high-quality nitride can be obtained without significantly damaging the reaction vessel. The present inventors have found that crystals can be obtained and that there is a great effect in improving the productivity.

That is, the above-described problems are solved by the following nitride crystal production method of the present invention.
[1] After filling the reaction vessel with at least a raw material and an ammonia solvent and sealing the reaction vessel, the reaction vessel is loaded into a pressure-resistant vessel, and the reaction vessel is brought to a supercritical and / or subcritical ammonia atmosphere. A nitride crystal manufacturing method for crystal growth in the reaction vessel,
A method for producing a nitride crystal, comprising a pressure adjustment region in a part of the reaction vessel.
[2] The method for manufacturing a nitride crystal according to [1], wherein the pressure adjustment region is formed at a position where the pressure adjustment region does not come into contact with the nitride crystal due to deformation due to pressure fluctuation during the manufacturing method.
[3] In the above [1] or [2], the reaction vessel includes a raw material region in which a raw material is disposed and a crystal growth region in which a seed crystal is disposed, and the pressure adjustment region is formed in the raw material region. The nitride crystal manufacturing method described.
[4] The nitride crystal according to any one of [1] to [3], wherein the reaction vessel is made of Pt _(100-x) Ir _(x) [X = 0 to 30 (wt%)]. Production method.
[5] The method for producing a nitride crystal according to any one of [1] to [4], wherein the pressure adjustment region has a structure that can be deformed by pressure.
[6] Any one of [1] to [5], wherein T1 <T2, where T1 is the thickness of the reaction vessel in the pressure adjustment region and T2 is the thickness of the reaction vessel outside the pressure adjustment region. A method for producing a nitride crystal as described in 1. above.
[7] The method for producing a nitride crystal according to [6], wherein T1 / T2 is 0.5 or more and less than 1.
[8] The method for producing a nitride crystal according to any one of [1] to [7], wherein the pressure adjustment region is formed of a material that is deformable by pressure.
[9] When the pressure adjustment region is made of Pt _(100-x1) Ir _(x1) and the portion other than the pressure adjustment region of the reaction vessel is made of Pt _(100-x2) Ir _(x2) , x1 <x2 The method for producing a nitride crystal according to [8], wherein both x1 and x2 are by weight.
[10] The method for producing a nitride crystal according to [9], wherein x2−x1 is 2 to 30%.
[11] The method for producing a nitride crystal according to any one of [8] to [10], wherein the pressure adjustment region is formed by annealing at least a part of a reaction vessel.
[12] The method for producing a nitride crystal according to any one of [1] to [11], wherein the pressure adjustment region is formed by welding and connecting at least one portion of the reaction vessel.

[13] After filling the reaction vessel with at least a raw material and an ammonia solvent and sealing the reaction vessel, the reaction vessel is placed in a pressure-resistant vessel, and the reaction vessel is brought to a supercritical and / or subcritical ammonia atmosphere. A reaction vessel for growing nitride crystals in the reaction vessel,
A reaction vessel comprising a pressure adjustment region in at least a part of the reaction vessel.
[14] The reaction container according to [13], wherein the pressure adjusting region is formed at a position where the pressure adjusting region does not contact the nitride crystal due to deformation due to pressure fluctuation when growing the nitride crystal.
[15] In the above [13] or [14], the reaction vessel includes a raw material region in which a raw material is disposed and a crystal growth region in which a seed crystal is disposed, and the pressure adjustment region is formed in the raw material region. The reaction vessel as described.
[16] The reaction container according to any one of [13] to [15], wherein the reaction container is made of Pt _(100-x) Ir _(x) [X = 0 to 30 (wt%)].
[17] The reaction container according to any one of [13] to [16], wherein the pressure adjustment region has a structure that can be deformed by pressure.
[18] Any one of [13] to [17], wherein T1 <T2 where T1 is a thickness of the reaction vessel in the pressure adjustment region and T2 is a thickness of the reaction vessel in a region other than the pressure adjustment region. The reaction container according to 1.
[19] The reaction container according to [18], wherein T1 / T2 is 0.5 or more and less than 1.
[20] The reaction container according to any one of [17] to [19], wherein the pressure adjustment region is formed of a material that can be deformed by pressure.
[21] When the pressure adjustment region is made of Pt _(100-x1) Ir _(x1) and the portion other than the pressure adjustment region of the reaction vessel is made of Pt _(100-x2) Ir _(x2) , x1 <x2 The reaction container according to [20], wherein both x1 and x2 are by weight.
[22] The reaction container according to [21], wherein x2-x1 is 2 to 30%.
[23] The reaction container according to any one of [20] to [22], wherein the pressure adjustment region is formed by annealing at least a part of the reaction container.
[24] The reaction container according to any one of [17] to [23], wherein the pressure adjustment region is formed by welding and connecting at least one part of the reaction container.
[25] A crystal manufacturing apparatus for growing a nitride crystal in a supercritical and / or subcritical ammonia atmosphere, the reaction vessel according to any one of [13] to [24], and the entire reaction vessel Crystal manufacturing apparatus including a pressure-resistant container for loading.

  According to the production method of the present invention, breakage of the reaction vessel can be easily prevented, and high-quality nitride crystals can be obtained without being damaged. For this reason, the reaction vessel can be used a plurality of times, which has a great effect on productivity. In addition, since the nitride crystal obtained by the production method of the present invention is uniform and of high quality, it is useful as a semiconductor crystal for a light emitting device or an electronic device. If the reaction container and crystal production apparatus of this invention are used, such a production method of this invention can be implemented simply.

It is a schematic diagram of the crystal manufacturing apparatus which can be used by this invention. It is sectional drawing of the reaction container which can be used by this invention. It is sectional drawing of another reaction container which can be used by this invention. It is sectional drawing of another reaction container which can be used by this invention.

  Hereinafter, a method for producing a semiconductor crystal of the present invention, and a reaction vessel and a crystal production apparatus used therefor will be described in detail. The description of the constituent elements described below may be made based on typical embodiments of the present invention, but the present invention is not limited to such embodiments. In the present specification, a numerical range represented by using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value.

  In the method for producing a nitride crystal of the present invention, a reaction vessel is filled with at least a raw material and an ammonia solvent and sealed, and then the reaction vessel is loaded into a pressure-resistant vessel, and supercritical and / or sublimation is carried out in the reaction vessel. A method for producing a nitride crystal in which crystal growth is performed in a critical ammonia atmosphere, wherein a pressure adjusting region is provided in a part of the reaction vessel.

  The crystal obtained by the crystal production method of the present invention is not particularly limited as long as it is a nitride single crystal. For example, a group III nitride crystal is preferable, and gallium nitride, aluminum nitride, indium nitride, and mixed crystals thereof are more preferable. . In this specification, gallium nitride (GaN) will be described as an example, but the manufacturing method of the present invention is not limited to this.

  As the crystal growth conditions when crystal growth is performed in a supercritical and / or subcritical ammonia atmosphere in the reaction vessel of the present invention, for example, for GaN, a raw material as disclosed in JP 2009-263229 A The conditions such as mineralizer, seed crystal, solvent, temperature, pressure, etc. can be preferably used. Moreover, also in the crystal manufacturing apparatus used for this manufacturing method and a specific procedure, the method disclosed in JP2009-263229A can be preferably used. The entire disclosure of this publication is incorporated herein by reference.

Specifically, the seed crystal, mineralizer, raw material, solvent, temperature, and pressure will be described below.
In crystal growth, it is preferable to use a seed crystal as the nucleus of crystal growth. Although it does not specifically limit as a seed crystal, The same kind as the crystal to grow is used preferably. Specific examples of the seed crystal include nitride single crystals such as gallium nitride (GaN), aluminum nitride (AlN), indium nitride (InN), and mixed crystals thereof.
The seed crystal can be determined in consideration of the lattice matching with the crystal to be grown. 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 the epitaxial growth is not particularly limited, and for example, a hydride vapor deposition method (HVPE method), a metal organic chemical vapor deposition method (MOCVD method), a liquid phase method, an ammonothermal method, or the like is adopted. be able to.

In the crystal growth of the present invention, it is preferable to use a mineralizer. 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.
The mineralizer used may be a basic mineralizer or an acidic mineralizer. Basic mineralizers include alkali metals, alkaline earth metals, compounds containing rare earth metals and nitrogen atoms, alkaline earth metal amides, rare earth amides, alkali nitride metals, alkaline earth metal nitrides, azide compounds, and other hydrazines. Class of salts. Preferably, it is an alkali metal amide, and specific examples include sodium amide (NaNH ₂ ), potassium amide (KNH ₂ ), and lithium amide (LiNH ₂ ). Moreover, as an acidic mineralizer, the compound containing a halogen element is preferable. Examples of mineralizers containing halogen elements include ammonium halide, hydrogen halide, ammonium hexahalosilicate, and hydrocarbyl ammonium fluoride, tetramethylammonium halide, tetraethylammonium halide, benzyltrimethylammonium 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, an additive (mineralizing agent) containing a halogen element is preferably an alkali halide, an alkaline earth metal halide, a metal halide, an ammonium halide, or a hydrogen halide, more preferably a halogenated. Alkalis, ammonium halides, group 13 metal halides and hydrogen halides are preferred, and ammonium halides, gallium halides and hydrogen halides are particularly preferred. Examples of the ammonium halide include ammonium chloride (NH ₄ Cl), ammonium iodide (NH ₄ I), ammonium bromide (NH ₄ Br), and ammonium fluoride (NH ₄ F).

As the mineralizer, it is preferable to use a mineralizer containing a fluorine element and at least one selected from other halogen elements composed of chlorine, bromine and iodine. These may be used individually by 1 type, and may mix and use multiple types suitably.
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 A combination of three elements such as iodine and fluorine may be used, or a combination of four elements such as chlorine, bromine, iodine and fluorine may be used. 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.

In the crystal growth, 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, with respect to 100 parts by mass of the halogen element-containing mineralizer, the mineralizer containing an alkali metal element or alkaline earth metal element is preferably 0.01 parts by mass or more, and 0.1 parts by mass More preferably, it is more preferably 0.2 parts by mass or more, more preferably 50 parts by mass or less, more preferably 20 parts by mass or less, and more preferably 5 parts by mass or less. More preferably.

In order to prevent impurities from being mixed into the nitride crystal grown by the crystal growth, the mineralizer can be used after being purified and dried as necessary. The purity of the mineralizer is usually 95% or higher, preferably 99% or higher, more preferably 99.99% or higher.
The amount of water and oxygen contained in the mineralizer 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 1.0 ppm or less. preferable.
When performing the crystal growth, aluminum halide, phosphorus halide, silicon halide, germanium halide, zinc halide, arsenic halide, tin halide, antimony halide, bismuth halide, etc. are used in a reaction vessel. 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.

  In the crystal growth of the present invention, a raw material containing an element constituting a nitride crystal to be grown 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.

  It is desirable that ammonia, which is the first solvent used for crystal growth by filling the reaction vessel, contains as little water and oxygen as possible. Specifically, 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.

In crystal growth, the entire pressure-resistant vessel including the inside of the reaction vessel is heated to a supercritical state and / or a subcritical state. In the supercritical state, the viscosity is generally low and it is more easily diffused than the liquid, but has the same solvating power as the 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 as a supercritical state, and in the crystal growth part, the temperature is changed so as to be in the subcritical state, and crystal growth utilizing the difference in solubility between the supercritical state and the subcritical state raw material is also performed. Is possible.
When 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 120 MPa or more, more preferably 150 MPa or more, and further preferably 180 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 500 ° C. or higher, more preferably 515 ° C. or higher, and further preferably 530 ° 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 region in the reaction vessel is preferably higher than the temperature of the crystal growth region. The temperature difference (| ΔT |) between the raw material region and the crystal growth region is preferably 5 ° C. or higher, more preferably 10 ° C. or higher, and 100 ° C. or lower from the viewpoint of crystallinity and productivity. It is preferably 90 ° C. or lower, more preferably 80 ° C. or lower. 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, the polycrystalline raw material and the seed crystal are used in the reaction vessel. In this case, subtract the volume of the seed crystal and the structure where it 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. Based on the liquid density at the boiling point of the remaining volume of solvent, it is usually 20% or more, preferably 30% or more, more preferably 40% or more, and usually 95% or less, preferably 80% or less, more preferably 70% or less.

Nitride crystals grow in the reaction vessel by heating and raising the temperature of the reaction vessel using an electric furnace having a thermocouple, etc., so that the reaction vessel is subcritical and / or supercritical in a solvent such as ammonia. It is performed by holding. 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 “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. It can be estimated in terms of temperature. The average value of the temperatures measured with these thermocouples is taken as the average temperature. Usually, the average value of the temperature of the raw material region and the temperature of the crystal growth region is taken 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.

  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 producing desired crystals, the 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. or higher, preferably −33 ° C. or higher, and is usually 200 ° C. or lower, preferably 100 ° C. or lower. Here, the valve may be opened by connecting a pipe to the pipe connection port of the valve connected to the reaction vessel, leading to 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, after crystal growth, it can cool to room temperature over 1 to 48 hours, for example by natural cooling or forced cooling.

  The pressure-resistant container needs to be made of a material excellent in strength in a high temperature environment, and the inner wall is preferably made of a metal containing Ni or Cr. In addition, the pressure-resistant container needs to have an internal volume capable of loading the entire reaction container used in the present invention. When the reaction vessel is loaded and sealed, there is a gap between the inner wall of the pressure-resistant vessel and the outer wall of the reaction vessel. The volume of the gap is 100% by volume when the inner volume of the reaction vessel is 100% by volume. It is preferably 5% by volume or more, more preferably 10% by volume or more, more preferably 200% by volume or less, and even more preferably 100% by volume or less. If the volume ratio of the void is too small, the distance between the outer wall of the reaction vessel and the inner wall of the pressure-resistant vessel becomes too narrow, and the outer wall of the reaction vessel may come into contact with the pressure-resistant vessel due to deformation of the capsule. It may be difficult to remove from the pressure resistant container. In addition, when the volume ratio of the voids is too large, the volume of the reaction vessel is reduced, and the amount of nitride crystals that can be produced and the size of the crystals are limited, which may reduce productivity.

The reaction vessel needs to be made of a material having excellent corrosion resistance against ammonia solvent, mineralizer, etc., and at least selected from the group consisting of Rh, Pd, Ag, Ir, Pt, Au, Ta, Ti and W. It is preferably made of one kind of metal or an alloy containing the metal as a main component. The alloy having the metal as a main component here means that the total content of Rh, Pd, Ag, Ir, Pt, Au, Ta, Ti and W in the alloy is 50% or more of the total weight of the alloy. Means 60% or more, more preferably 70% or more. The reaction vessel preferably contains at least one of Ir, Pt, and Ta among the above metal group, and more preferably contains at least one of Ir and Pt. More preferably, it is a reaction vessel made of Pt or Pt _(100-x) Ir _(x) [x = 0 to 30 (wt%)] alloy. Among these, x is preferably 3 or more, more preferably 5 or more, preferably 20 or less, and more preferably 15 or less.

Although the specific structure of the reaction vessel is not particularly limited, a typical reaction vessel is provided with a raw material region for containing a raw material for crystal growth and a crystal growth region for growing crystals. A seed crystal can be installed in the crystal growth region, and the crystal growth region and the raw material region are generally separated by a baffle plate.
The reaction vessel used in the present invention is characterized by having a pressure adjustment region at least partially. The pressure adjustment region here means that the pressure applied to the reaction vessel is larger because the shape is more easily changed than the region other than the pressure adjustment region (non-pressure adjustment region) with respect to the pressure fluctuation in the production method of the present invention. It means an area that can be absorbed. That is, the pressure adjustment region is likely to be deformed with a smaller pressure fluctuation than the other regions. For example, the pressure adjustment region may be formed of a material that can be deformed by pressure, or may have a structure that can be deformed by pressure.

When the pressure adjustment area is formed of a material that can be deformed by pressure, use a material that is easily deformable with respect to the pressure change in the pressure adjustment area, and use a material that is not easily deformable with respect to the pressure change in the other areas. Can do. For example, in the case of a Pt—Ir alloy, if the content of Ir is increased, it becomes more difficult to deform with respect to a pressure change, so the pressure adjustment region is Pt _(100−x1) Ir _(x1) When a reaction vessel other than the region is formed from Pt _(100-x2) Ir _(x2) , x1 <x2 (x1 and x2 are both wt%) can be mentioned. X2-x1 which is the difference in Ir content is preferably set to 2% or more, more preferably set to 5% or more in order to give a sufficient difference in the ease of deformation due to pressure change, In order to obtain an appropriate strength, it is preferably set to 30% or less, and more preferably set to 15% or less. A specific example of the pressure adjustment region formed by selecting the material is shown in FIG. In the drawing, the pressure adjustment region 23 is indicated by hatching, and the non-pressure adjustment region 24 is indicated by white. FIG. 2A shows the pressure adjustment region 23 in which the side wall and bottom of the reaction vessel defining the raw material region 8 are made of a material that is easily deformed by pressure. FIG. 2B shows a case where the seed crystal 4 is installed only at the upper end of the crystal growth region 7 and only the periphery thereof is set as the non-pressure adjustment region 24 and the others are set as the pressure adjustment region 23. FIG. 2C shows a case where the seed crystal 4 is installed only below the crystal growth region 7, and only the inner wall around the seed crystal 4 is used as the non-pressure adjustment region 24, and the others are used as the pressure adjustment region 23. FIG. 2D shows the pressure adjustment region 23 in which only the lower wall surface of the raw material region 8 is made of a material that is easily deformed by pressure. As described above, the pressure adjustment region can be formed at an arbitrary position.

Moreover, after forming the whole reaction container with the same material, the method of annealing the part used as a pressure adjustment area | region at high temperature is also employable. The annealing conditions are not particularly limited as long as the material can be deformed. For example, the metal may be heated at 500 to 1200 ° C. for 1 to 12 hours in the atmosphere, nitrogen, or an inert gas atmosphere. Note that “annealing” in this specification is not limited as long as heat treatment is performed on the material so that the material can be softened and the spreadability can be improved as compared with the material before the heat treatment.
Furthermore, a method of forming the pressure adjustment region by welding or the like can be employed. By welding, it can be set as the area | region which is easy to deform | transform with respect to a pressure change. The welding method is not particularly limited, and examples thereof include TIG welding and gas welding.

When the pressure adjustment area has a structure that can be deformed by pressure, a structure that is easily deformed by a pressure change is formed in the pressure adjustment area, and a structure that is not easily deformed by a pressure change is formed in the other areas. be able to. Examples of the deformable structure include a bellows and a structure made thinner than the thickness of the reaction vessel other than the pressure adjustment region.
About the specific structure of a bellows, the structure etc. which are used for a hydrothermal synthesis method can be selected suitably, and can be employ | adopted. Specifically, the bellows 25 shown in FIG. 3 can be illustrated. The formation position of the bellows is not particularly limited as long as it does not damage the obtained nitride crystal. For example, it may be formed below the source region 8 as shown in FIG. 3A, or may be formed above the crystal growth region 7 as shown in FIG. If it is formed below the raw material region 8, even if the pressure adjustment region is contracted or broken, there is an advantage that the crystal is hardly affected because it is far from the crystal. On the other hand, if it is formed above the crystal growth region 7, even if polycrystals or the like are deposited in the openings of the baffle plate 6 and the air permeability between the crystal growth region 7 and the raw material region 8 is lowered, the crystal growth region There is an advantage that the nitride crystal formed in 7 is easy to protect. The bellows 25 may be formed both below the raw material region 8 and above the crystal growth region 7. In addition, the material of bellows may be the same as the wall surface of another reaction container, and may differ.

  When the pressure adjustment region is formed by adjusting the thickness of the reaction vessel, T1 <T2 when the thickness of the reaction vessel in the pressure adjustment region is T1 and the thickness of the reaction vessel outside the pressure adjustment region is T2. Like that. T1 is preferably 0.2 mm or more and more preferably 0.3 mm or more because of strength and ease of handling. Further, T2 is preferably 2.0 mm or less, and more preferably 1.0 mm or less because of cost and ease of handling. Further, the ratio of the thicknesses of T1 and T2 (T1 / T2) is preferably 0.5 or more because it is easy to balance the maintenance of the required strength and the ease of deformation. It is preferable to do. A specific example of the pressure adjustment region in which the thickness is adjusted is shown in FIG. 4 (a) and 4 (b) show a case where the thickness of the side wall and the bottom of the reaction vessel defining the raw material region 8 is reduced. In FIG. 4A, the inner wall of the crystal growth region 7 is reduced by increasing the thickness of the side wall of the reaction vessel defining the non-pressure adjusting region 24 so as to increase inward. In FIG. 4 (b), the side wall of the reaction vessel that defines the non-pressure adjusting region 24 is thickened so as to be thickened outward so that the inner diameter of the crystal growth region 7 does not change from the raw material region 8. FIG. 4C shows the pressure adjustment region 23 by thinning only the bottom of the raw material region 8, and FIG. 4D shows the pressure by thinning only a part of the lower side of the side wall defining the raw material region 8. This is the adjustment area 23. By configuring as shown in FIGS. 4C and 4D, it is possible to limit a portion deformed by pressure adjustment to an arbitrary position.

These deformable materials and structures may be employed singly or in combination as a pressure adjustment region. For reasons such as ease of processing, ease of handling, and maintenance of a simple structure, the material of the pressure adjustment region is Pt _(100-x1) Ir _(x1) , and the material of the reaction vessel other than the pressure adjustment region is Pt _{( 100-x2) When} Ir _(x2) , x1 <x2 is formed, the pressure adjustment region is formed by annealing, and the thickness (T1) of the pressure adjustment region is the thickness of the reaction vessel other than the pressure adjustment vessel (T2) It is preferable to make it thinner (T1 <T2).

  As long as the effects of the present invention can be achieved, the pressure adjustment region may be formed in any part of the reaction vessel. Moreover, the pressure adjustment area | region may be formed in one place, and as shown in FIG.2 (c), you may form in multiple places. In order to prevent damage to the obtained crystal, the pressure adjustment region is preferably formed at a position where it does not contact the nitride crystal due to deformation due to pressure fluctuation during the manufacturing method of the present invention.

  When the external pressure of the reaction vessel rises and the reaction vessel is crushed, the grown nitride crystals are prevented from being crushed and the reaction vessel is damaged, and the second solvent outside the reaction vessel is placed inside the reaction vessel. In order to prevent crystal contamination due to inflow into the reactor, the pressure adjustment region is preferably formed in the raw material region of the reaction vessel. The pressure adjustment region is preferably 10 to 100% of the inner surface area of the raw material region in the reaction vessel (the inner surface area of the reaction vessel with which the contents can contact in the raw material region), and preferably 20 to 100%. More preferred. In the case where the adjustment region is provided in the crystal growth region, it is preferable that a portion where no seed crystal is arranged is formed in the crystal growth region and the pressure adjustment region is provided in that portion in order to prevent damage to the nitride crystal. For example, the seed crystal is not disposed at the uppermost part of the crystal growth region (near the closed end on the side opposite to the raw material region), and that portion can be used as the pressure adjustment region. The pressure adjustment region is preferably 4% or more, more preferably 8% or more, of the total inner surface area in the reaction vessel (the total inner surface area of the reaction vessel with which the contents can come into contact). % Or more is more preferable, 70% or less is preferable, and 60% or less is more preferable.

  FIG. 1 shows an example of the crystal production apparatus of the present invention. The type of the second solvent that fills the gap between the reaction vessel and the pressure-resistant vessel in the present invention is not limited as long as it is a solvent that can bring the inside and outside of the reaction vessel to substantially the same pressure. As such a second solvent, for example, ammonia, water, alcohol, carbon dioxide and the like can be used. In order to reduce the pressure difference between the inside and outside of the reaction vessel, the second solvent has a property close to that of ammonia used as the first solvent in the reaction vessel (that is, the filling rate and the temperature-pressure are constant under a constant internal volume condition). The solvent is preferably a solvent whose relationship is close to the temperature-pressure change of ammonia, and it is particularly preferable to use ammonia. The reason for this is that when a solvent with similar properties is used, the pressure inside and outside the reaction vessel is kept approximately the same when the temperature is raised to perform crystal growth reaction by dissolution and precipitation of the raw materials, especially during the temperature rise process. This is because it becomes easy. Usually, it is preferable to use the same solvent on the inside and outside of the reaction vessel, and to make the filling rate of the solvent in the reaction vessel and the filling rate of the gap between the reaction vessel and the pressure-resistant vessel substantially the same. Specifically, when the filling rate is expressed as a percentage, the difference between the filling rate of the solvent in the reaction vessel and the filling rate of the gap between the reaction vessel and the pressure-resistant vessel is preferably within ± 10%, More preferably within ± 5%. More strictly, the temperature of ammonia inside and outside the reaction vessel may differ depending on the design of the heating furnace and the arrangement of the reaction vessel in the pressure-resistant vessel. Therefore, the filling rate is changed according to each temperature. More preferably, the pressure inside and outside the reaction vessel is approximately the same.

  When the second solvent filled in the space between the reaction vessel and the pressure-resistant vessel is ammonia, usually the ammonia does not come into direct contact with the raw material, so there is no particular problem with respect to physical properties such as impurities. In order to make the physical properties of ammonia in the reaction vessel and the ammonia filled in the gap between the reaction vessel and the pressure-resistant vessel substantially equal, it is necessary to reduce the amount of water and oxygen contained in the ammonia as much as possible. desirable. The total content of water and oxygen is preferably 1000 ppm or less, more preferably 100 ppm or less. Reducing the amount of water and oxygen as much as possible is also effective from the viewpoint of suppressing corrosion of the pressure resistant container.

  In the study by the present inventors, when a specific material is used for the pressure-resistant vessel and the reaction vessel, the pressure outside the reaction vessel tends to increase, and as a result, the pressure balance inside and outside the reaction vessel I came to find the problem that it is easy to collapse. Although this factor is not clear, the following can be considered. In general, a material having excellent corrosion resistance such as a noble metal such as Pt is used as a reaction vessel, whereas a material having excellent strength in a high temperature environment including Ni, Cr and the like is used as a pressure resistant vessel. . That is, the ammonia inside the reaction vessel is in contact with only the noble metal, but the ammonia outside the reaction vessel is in contact with a metal capable of decomposing ammonia such as Ni and Cr in addition to the noble metal. Therefore, when the temperature is increased to perform the crystal growth reaction, it is considered that a small amount of ammonia outside the reaction vessel is decomposed to become nitrogen and hydrogen, so that the pressure slightly increases. .

  In such a case, by using a reaction vessel having at least a part of the pressure adjustment region, a nitride crystal grown by deformation of the pressure adjustment region of the reaction vessel away from the nitride crystal in the crystal growth region A nitride crystal can be obtained without damaging the substrate. The deformed pressure adjustment region can be used as it is for the next nitride crystal growth as long as the degree of deformation is slight. Further, the deformed pressure adjustment region can be used for the growth of the next nitride crystal after the original shape is restored. As a restoration method, for example, a method of mechanically molding using a mold, a method of increasing the internal pressure by filling water, oil, or gas into a reaction vessel to expand, a correction by a roll molding machine The method etc. can be mentioned. It is also possible to reuse only the non-pressure adjustment region by cutting the deformed pressure adjustment region and joining a new pressure adjustment region.

  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>
A GaN crystal was manufactured by the ammonothermal method using the crystal manufacturing apparatus shown in FIG. Here, the RENE41 autoclave 1 having an inner dimension of 30 mm in diameter and 450 mm in length is used as a pressure-resistant container, and a cylindrical inner cylinder 2 having an inner dimension of 25 mm in diameter, a length of 300 mm, and a thickness of 0.6 mm. Was used as a reaction vessel. The inner cylinder 2 includes a crystal growth region 7 made of a Pt90% -Ir10% alloy having a length of 160 mm and a raw material region 8 made of Pt having a length of 140 mm. The raw material region 8 is used as the pressure adjustment region 23. It functions (see FIG. 2 (a)). In a state where the inner cylinder 2 is inserted into the autoclave 1 and the autoclave lid 3 is closed, a gap (autoclave inner volume−inner cylinder volume) that can be filled with the second solvent is provided between the autoclave 1 and the inner cylinder 2. About 70 cm ^{3 was} present.
Polycrystalline GaN particles were placed as the raw material 5 in the lower region (raw material region) 8 of the inner cylinder 2 in a sufficiently dry nitrogen atmosphere glove box. Further, a platinum baffle plate 6 (opening ratio 20%) was placed between the lower raw material region 8 and the upper crystal growth region 7. As the seed crystal 4, four hexagonal GaN single crystals (10 mm × 5 mm × 0.3 mm) grown by the HVPE method and two particulate crystals (about 5 mm × 5 mm × 5 mm) spontaneously nucleated by the HVPE method were used. . These seed crystals 4 were suspended from a platinum seed crystal support frame by a platinum wire having a diameter of 0.2 mm, and placed in the crystal growth region 7 at the upper part of the inner cylinder. After vacuum degassing the inner cylinder 2 using a vacuum pump and purging the inner cylinder 2 with nitrogen gas five times, liquid nitrogen is added so that the concentration of HCl gas as a mineralizer is 3 mol% with respect to ammonia. Filled at temperature. Next, NH ₃ was filled as a liquid corresponding to about 58% of the effective volume of the inner cylinder 2 (converted to an NH ₃ density of −33 ° C.), and then the inner cylinder 2 was sealed.

The inner cylinder 2 was inserted into the autoclave 1 and the autoclave lid 3 was closed. After the inside of the autoclave 1 was vacuum degassed and nitrogen gas purge was performed several times, NH ₃ was filled into the autoclave 1 as a second solvent. At this time, NH ₃ was filled as a liquid corresponding to about 60% of the space between the autoclave 1 and the inner cylinder 2 (converted with an NH ₃ density of −33 ° C.).
Subsequently, the autoclave 1 was accommodated in an electric furnace composed of heaters 11 and 12 divided into two parts in the vertical direction. The temperature of the crystal growth region 7 on the outer surface of the autoclave 1 measured with the thermocouple 16 is 620 ° C., and the temperature of the raw material region measured with the thermocouple 17 is 640 ° C. (temperature difference 20 ° C .: average temperature 630 ° C.). The temperature was raised over time, and after reaching the set temperature, the temperature was maintained for 4 days. The pressure in the autoclave 1 was 230 MPa.

Then, it naturally cooled over 8 hours until the temperature of the outer surface of the autoclave 1 returned to room temperature, the valve 9 attached to the autoclave 1 was opened, and NH ₃ in the autoclave 1 was removed. Thereafter, the autoclave 1 was weighed to confirm that NH ₃ was discharged, and then the autoclave lid 3 was opened and the inner cylinder 2 was taken out. A hole was made in a tube (not shown) attached to the upper part of the inner cylinder 2 to remove NH ₃ from the inner cylinder 2.
Although the raw material area 8 of the inner cylinder 2 contracted, the crystal growth area 7 did not deform, and the crystals could be taken out safely. Further, the contracted raw material area 8 could be easily restored to its original shape and reused. It was also possible to reuse the crystal growth region by replacing the raw material region 8 without restoring it.
When the crystals were confirmed, gallium nitride crystals were uniformly deposited on the entire surface of all seed crystals. As a result of X-ray diffraction measurement of the gallium nitride crystal grown on the seed crystal, it was confirmed that the crystal system was hexagonal and contained no cubic GaN.

<Example 2>
As shown in Table 1, the crystal growth region 7 is made of a Pt80% -Ir20% alloy having a thickness of 0.5 mm, and the raw material region 8 is made of Pt90% -Ir10% having a thickness of 0.5 mm. Crystal growth is performed under the same conditions as in Example 1 except that the inner cylinder 2 (see FIG. 2A) in which the raw material region 8 functions as the pressure adjustment region 23 is used.
The raw material region 8 of the inner cylinder 2 contracts, but the crystal growth region 7 does not deform, and the crystal can be taken out safely.

<Example 3>
As shown in Table 1, it is composed of a crystal growth region 7 made of a Pt90% -Ir10% alloy having a thickness of 0.6 mm and a raw material region 8 made of Pt90% -Ir10% having a thickness of 0.45 mm. Crystal growth is performed under the same conditions as in Example 1 except that the inner cylinder 2 (see FIG. 4B) in which the raw material region 8 functions as the pressure adjustment region 23 is used.
The raw material region 8 of the inner cylinder 2 contracts, but the crystal growth region 7 does not deform, and the crystal can be taken out safely.

<Example 4>
As shown in Table 1, the material of the inner cylinder 2 is Pt90% -Ir10% (thickness is 0.6 mm), and only the raw material region 8 of the inner cylinder 2 is annealed in air at 1100 ° C. for 10 hours to adjust the pressure. Crystal growth is performed under the same conditions as in Example 1 except that the RENE41 autoclave 1 having a diameter of 70 mm and a length of 1050 mm is used as the pressure resistant container.
The raw material region 8 of the inner cylinder 2 contracts, but the crystal growth region 7 does not deform, and the crystal can be taken out safely.

<Comparative Example 1>
As described in Table 1, crystal growth is performed under the same conditions as in Example 1 except that the inner cylinder 2 made of Pt having a thickness of 0.6 mm and having no pressure adjustment region is used.
The inner cylinder 2 contracts in both the raw material region 8 and the crystal growth region 7, the inner wall of the reaction vessel comes into contact with the crystal, and a crack is generated in a part of the crystal.

<Comparative Example 2>
As described in Table 1, crystal growth was performed in the same manner as in Example 1 except that the inner cylinder 2 made of Pt90% -Ir10% having a thickness of 0.45 mm and having no pressure adjustment region was used. went.
In the inner cylinder 2, both the raw material region 8 and the crystal growth region 7 contracted, the inner wall of the reaction vessel contacted the crystal, or the crystals collided with each other, and a crack occurred in a part of the crystal.
According to Examples 1 to 4, by installing a pressure adjustment region in at least a part of the reaction vessel, it can be taken out without damaging the grown crystal, while in Comparative Reaction Examples 1 and 2, When the pressure adjustment region is not provided, there is a problem that the entire reaction vessel contracts, the inner wall of the reaction vessel comes into contact with the crystal, and a crack occurs in the crystal.

  INDUSTRIAL APPLICABILITY The present invention is useful for growing group III nitride bulk single crystals, particularly GaN bulk single crystals. According to the production method of the present invention, the pressure balance inside and outside the reaction vessel can be easily maintained, and a high-quality nitride crystal can be obtained. Furthermore, it is possible to use the reaction vessel a plurality of times, and significant improvement can be expected in both time and cost. Therefore, the present invention has very high industrial applicability.

1 Pressure resistant container (autoclave)
2 reaction vessel (inner cylinder)
3 Autoclave lid 4 Seed crystal 5 Raw material 6 Baffle plate 7 Crystal growth zone 8 Raw material zone 9 Valve 10 Insulating material 11 Crystal growth zone heater 12 Raw material zone heater 13 Conduit 14 Exhaust pipe 15 Vacuum pump 16 Thermocouple 1
17 Thermocouple 2
18 Rupture plate 19 Mass flow meter 20 Ammonia cylinder 21 Nitrogen cylinder 22 Pressure sensor 23 Pressure adjustment area 24 Non-pressure adjustment area 25 Bellows

Claims (21)

After filling the reaction vessel with at least a raw material and an ammonia solvent and sealing the reaction vessel, the reaction vessel is charged into a pressure-resistant vessel, and the reaction vessel is filled with a supercritical and / or subcritical ammonia atmosphere, A method for producing a nitride crystal in which a crystal is grown in a reaction vessel,
Providing a pressure adjustment region in a part of the reaction vessel;
The pressure adjustment region is formed of a material that can be deformed by pressure, and the pressure adjustment region is made of Pt _(100-x1) Ir _(x1) , and a portion other than the pressure adjustment region of the reaction vessel is Pt. _{(100-x2) Ir (x2} ) Tona Ri, x1 <x2, characterized in that a (x1, x2 both wt%), production method for nitride crystals. After filling the reaction vessel with at least a raw material and an ammonia solvent and sealing the reaction vessel, the reaction vessel is charged into a pressure-resistant vessel, and the reaction vessel is filled with a supercritical and / or subcritical ammonia atmosphere, A method for producing a nitride crystal in which a crystal is grown in a reaction vessel,
Providing a pressure adjustment region in a part of the reaction vessel;
The pressure regulation region is formed of a material that can be deformed by pressure, and the pressure regulation region is formed by annealing at least a part of a reaction vessel. Method.   3. The method for producing a nitride crystal according to claim 1, wherein the pressure adjustment region is formed at a position where the pressure adjustment region does not contact the nitride crystal due to deformation due to pressure fluctuation during the production method.   The reaction container includes a raw material region in which a raw material is disposed and a crystal growth region in which a seed crystal is disposed, and the pressure adjustment region is formed in the raw material region. The nitride crystal manufacturing method described. The manufacturing method of the nitride crystal | crystallization of any one of Claims 1-4 with which the said reaction container consists of Pt _(100-x) Ir _(x) [X = 0-30 (weight%)].   The method for producing a nitride crystal according to claim 1, wherein the pressure adjustment region has a structure that can be deformed by pressure.   The nitride according to any one of claims 1 to 6, wherein T1 <T2, where T1 is a thickness of the reaction vessel in the pressure adjustment region and T2 is a thickness of the reaction vessel other than the pressure adjustment region. Crystal production method.   The method for producing a nitride crystal according to claim 7, wherein T1 / T2 is 0.5 or more and less than 1.   The method for producing a nitride crystal according to claim 1, wherein x2-x1 is 2 to 30%.   The method for producing a nitride crystal according to any one of claims 1 to 9, wherein the pressure adjustment region is formed by welding and connecting at least one portion of a reaction vessel. After filling the reaction vessel with at least raw materials and an ammonia solvent and sealing the reaction vessel, the reaction vessel is placed in a pressure-resistant vessel, and the reaction vessel is placed in a supercritical and / or subcritical ammonia atmosphere to react. A reaction vessel for growing nitride crystals in the vessel,
Providing a pressure adjustment region in at least a part of the reaction vessel;
The pressure adjustment region is formed of a material that can be deformed by pressure, and the pressure adjustment region is made of Pt _(100-x1) Ir _(x1) , and a portion other than the pressure adjustment region of the reaction vessel is Pt. _{(100-x2) Ir (x2} ) Tona Ri, x1 <x2 reaction vessel, characterized in that the (x1, x2 both wt%). After filling the reaction vessel with at least raw materials and an ammonia solvent and sealing the reaction vessel, the reaction vessel is placed in a pressure-resistant vessel, and the reaction vessel is placed in a supercritical and / or subcritical ammonia atmosphere to react. A reaction vessel for growing nitride crystals in the vessel,
Providing a pressure adjustment region in at least a part of the reaction vessel;
A reaction vessel, wherein the pressure adjustment region is formed of a material that can be deformed by pressure, and the pressure adjustment region is formed by annealing at least a part of the reaction vessel.   The reaction vessel according to claim 11 or 12, wherein the pressure adjusting region is formed at a position where the pressure adjusting region does not contact the nitride crystal due to deformation due to pressure fluctuation when growing the nitride crystal.   The said reaction container is equipped with the raw material area | region which arrange | positions a raw material, and the crystal growth area | region which arrange | positions a seed crystal, The said pressure regulation area | region is formed in the said raw material area | region, The statement to any one of Claims 11-13 The reaction vessel as described. The reaction container according to any one of claims 11 to 14, wherein the reaction container is made of Pt _(100-x) Ir _(x) [X = 0 to 30 (% by weight)].   The reaction container according to claim 11, wherein the pressure adjustment region has a structure that can be deformed by pressure.   The reaction container according to any one of claims 11 to 16, wherein T1 <T2, where T1 is a thickness of the reaction container in the pressure adjustment region and T2 is a thickness of the reaction container in a region other than the pressure adjustment region. .   The reaction container according to claim 17, wherein T1 / T2 is 0.5 or more and less than 1.   The reaction container according to claim 11, wherein x2-x1 is 2 to 30%.   The reaction container according to any one of claims 16 to 19, wherein the pressure adjustment region is formed by welding and connecting at least one part of the reaction container. A crystal manufacturing apparatus for growing a nitride crystal in a supercritical and / or subcritical ammonia atmosphere,
A crystal production apparatus comprising the reaction vessel according to any one of claims 11 to 20 and a pressure-resistant vessel for loading the entire reaction vessel.