JP2013107803A - Apparatus and method for growing crystal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To miniaturize and simplify a crystal growth apparatus while securing uniformity of crystals with practical size and other qualities, in the crystal growth apparatus using a flux method.SOLUTION: There is provided a crystal growth apparatus having a container housing a liquid including crystal raw material atoms; and an elastic wave propagation means propagating the elastic wave as a traveling wave along the liquid contact surface in contact with the liquid. The inner surface of the container may be exemplified as the liquid contact surface. The elastic wave propagation unit may have a piezoelectric body disposed in contact with the container, thereby the elastic wave can be propagated along the liquid contact surface by applying alternating electric field on the piezoelectric body. A plurality of piezoelectric bodies may be disposed, and by regulating phases of the plurality of the alternating electric fields respectively applied on the plurality of piezoelectric bodies, the elastic wave can be propagated as the traveling wave.

Description

  The present invention relates to a crystal growth apparatus and a crystal growth method.

  As a method for forming a bulk crystal of a gallium nitride based semiconductor, a bulk crystal growth method using an alkali metal such as Na as a flux (hereinafter sometimes simply referred to as “flux method”) is known. For example, in Patent Document 1, a reaction vessel containing an alkali metal element and a group III element is heated to form a metal element flux, a nitrogen-containing gas is introduced into the reaction vessel, and the group III element and nitrogen are introduced into the flux. A method for producing a group III element nitride single crystal is disclosed in which a group III element nitride single crystal is grown by reaction. In the production method, there is a description that it is possible to produce a high-quality crystal having a uniform dislocation density and a low dislocation density by shaking the reaction vessel and stirring the flux.

  Patent Document 2 discloses a method for producing a group III metal nitride crystal by a flux method similar to that of Patent Document 1. In the method, there is a description that the unevenness of the crystal surface can be reduced by avoiding the stagnation of the melt near the surface of the seed crystal. As means for avoiding stagnation of the melt, it is disclosed that an ultrasonic generator is provided in the middle of a pipe connected to a crucible. The vibration generated by the ultrasonic generator is transmitted to the crucible through the pipe, and the seed crystal also vibrates with the vibration of the crucible, resulting in convection in the melt, thereby suppressing variations in group III metal and N ion concentration, There is a description that stagnation of the melt near the surface of the seed crystal can be avoided.

  Patent Document 3 and Patent Document 4 have a description that a liquid is transported and stirred in a microfluidic device by an ultrasonic traveling wave, and Patent Document 5 describes an annular vibrator with an ultrasonic phase. There is a description that a traveling wave that circulates around the annulus is generated by oscillating and shifting, and a vortex is generated in the fluid.

International Publication WO 2004/083498 JP 2005-175276 A JP 2009-5609 A JP 2009-31069 A Japanese Patent Laid-Open No. 11-260781

  Formation of a gallium nitride single crystal by the flux method is performed, for example, by placing a mixed melt of gallium and an alkali metal heated to 500 ° C. or higher in a nitrogen gas environment of 10 atm or higher, and gallium in the mixed melt. This is done by reacting nitrogen that has entered the liquid to precipitate gallium nitride. The flux method in the case of using sodium as the alkali metal is hereinafter referred to as “Na flux method”. A seed crystal may be used for precipitation of the gallium nitride single crystal.

  In the flux method, since nitrogen gas enters from the surface of the mixed melt, parasitic precipitation (unintended crystal growth) is likely to occur near the surface of the liquid. When parasitic precipitation occurs, nitrogen gas is consumed by the precipitation, and it becomes difficult to supply sufficient nitrogen to the intended growth point of the crystal, which may cause the quality of the formed crystal to deteriorate. .

  As a countermeasure, a method of stirring the mixed melt can be considered, but since the growth of gallium nitride crystals by the flux method is performed in a high temperature and high pressure environment, it is difficult to attach a mechanical stirring mechanism to the growth apparatus. In order to ensure the uniformity of a crystal having a proper size, a method of swinging the entire growth apparatus as described in Patent Document 1 must be employed. However, the method of swinging the entire growth apparatus becomes difficult to introduce when the apparatus is large and the installation location is limited. In addition, an increase in the size of the device increases costs and adversely affects the competitiveness of the product.

  An object of the present invention is to provide a technology capable of miniaturizing and simplifying a crystal growth apparatus while ensuring uniformity and other qualities of a practical size crystal in a crystal growth apparatus using a flux method. is there. In the flux method, alkali metals such as Na and K or alkaline earth metals can be used as a solvent, and other group III atoms can be used as a crystal raw material instead of gallium. This is a common problem regardless of the difference in the solvent or the crystal raw material, and the object of the present invention is applicable even when the solvent or the crystal raw material is different.

  In order to solve the above problems, in the first aspect of the present invention, an elastic wave that propagates an elastic wave as a traveling wave to a container that contains a liquid containing crystal source atoms and a liquid contact surface that is in contact with the liquid. A crystal growth apparatus having propagation means.

  An example of the liquid contact surface is the inner surface of the container. The elastic wave propagation means may include a piezoelectric body disposed in contact with the container, and the elastic wave can be propagated to the liquid contact surface by applying an alternating electric field to the piezoelectric body. . Alternatively, the elastic wave propagation means may include a piezoelectric body that is a part of the container, and the elastic wave is propagated to the liquid contact surface by applying an alternating electric field to the piezoelectric body. it can. A plurality of the piezoelectric bodies may be provided, and the elastic wave can be propagated as a traveling wave by adjusting the phase of the alternating electric field applied to each of the plurality of piezoelectric bodies. When two piezoelectric bodies selected from the plurality of piezoelectric bodies are located at a distance L, and the phases of alternating electric fields applied to the two piezoelectric bodies are different by 90 degrees or 270 degrees, Between the wavelength λ of the elastic wave and the distance L, there can be a relationship of L = λ (n + 1/4), where n is an integer. The container may have a circular path where an elastic wave propagating on the liquid contact surface reaches an original position. In this case, the piezoelectric wave is enhanced so that the amplitude of the elastic wave propagated through the circular path is enhanced. The phase of the alternating electric field applied to the body may be adjusted.

  An elastic body installed inside the container may be further included. In this case, the surface of the elastic body can be exemplified as the liquid contact surface. The elastic wave propagation means may include a piezoelectric body disposed in contact with the elastic body, and applying the alternating electric field to the piezoelectric body causes the elastic wave to propagate to the liquid contact surface. it can. Alternatively, the elastic wave propagation means may include a piezoelectric body that is a part of the elastic body, and the elastic wave is propagated to the liquid contact surface by applying an alternating electric field to the piezoelectric body. Can do. A plurality of the piezoelectric bodies may be provided, and the elastic wave can be propagated as a traveling wave by adjusting the phase of the alternating electric field applied to each of the plurality of piezoelectric bodies. When two piezoelectric bodies selected from the plurality of piezoelectric bodies are located at a distance L, and the phases of alternating electric fields applied to the two piezoelectric bodies are different by 90 degrees or 270 degrees, Between the wavelength λ of the elastic wave and the distance L, there can be a relationship of L = λ (n + 1/4), where n is an integer. The elastic body may have a circular path where an elastic wave propagating through the liquid contact surface reaches an original position.In this case, the amplitude of the elastic wave propagated through the circular path is enhanced. The phase of the alternating electric field applied to the piezoelectric body may be adjusted.

  There may be further provided a vibration isolating means located away from the elastic wave propagation means, and the vibration isolating means absorbs an elastic wave that has propagated through the liquid contact surface and reached the vibration isolating means. It may be a member. Alternatively, the vibration isolator may further include a vibration isolating unit positioned away from the elastic wave propagation unit, and the vibration isolating unit vibrates to cancel the elastic wave that has propagated through the liquid contact surface and reached the vibration isolating unit. A generated piezoelectric body may be used.

Gas supply means for supplying the gas containing the crystal source atoms at a pressure of atmospheric pressure or higher, and pressure maintaining means for maintaining the pressure of the gas at the gas-liquid interface where the gas and the liquid are in contact with each other at atmospheric pressure or higher. And may further include You may further have a heating means to heat the said container. Examples of the Curie point of the piezoelectric body included in the elastic wave propagation means include 500 ° C. or higher. Examples of the piezoelectric body include one made of one or more materials selected from the group consisting of La ₃ Ga ₅ SiO ₁₄ , LiNbO ₃ , SiO ₂ , AlN, and AlN / Sc. Examples of the member constituting the liquid contact surface include those made of one or more materials selected from the group consisting of AlN, SiC, graphite, BN, Al ₂ O ₃ and SiO ₂ .

  In the second aspect of the present invention, the liquid containing the crystal source atoms is contained in the container, and an elastic wave is propagated as a traveling wave to the liquid contact surface in contact with the liquid. Contacting a seed crystal of the crystal to grow the crystal.

  In the step of growing the crystal, a gas containing raw material atoms of the crystal may be supplied to the container, and the crystal may be grown while maintaining the pressure of the gas at atmospheric pressure or higher. Examples of the liquid include those containing gallium atoms and alkali metal atoms, examples of the gas include those containing nitrogen atoms, and examples of the crystal include growing a gallium nitride single crystal.

It is the schematic which looked at the crystal growth apparatus 100 from upper direction. It is the schematic sectional drawing which looked at crystal growth device 100 from the front. It is the schematic sectional drawing which looked at crystal growth device 200 from the front. It is the schematic which looked at the crystal growth apparatus 300 from upper direction. It is the schematic sectional drawing which looked at crystal growth device 300 from the front. It is the schematic sectional drawing which looked at crystal growth device 400 from the front. It is the schematic sectional drawing which looked at crystal growth device 500 from the front. It is the schematic which looked at the crystal growth apparatus 600 from upper direction. It is the schematic sectional view which looked at crystal growth device 600 from the front. It is the schematic which looked at the crystal growth apparatus 700 from upper direction. It is the schematic sectional view which looked at crystal growth device 700 from the front. It is the schematic which looked at the crystal growth apparatus 800 from upper direction. It is the schematic sectional view which looked at crystal growth device 800 from the front.

  FIG. 1 is a schematic view of the crystal growth apparatus 100 as viewed from above, and FIG. 2 is a schematic cross-sectional view of the crystal growth apparatus 100 as viewed from the front. The crystal growth apparatus 100 includes a container 102, a piezoelectric body 108, a gas supply unit 110, a pressure maintaining unit 112, and a heating unit 114. The gas supply means 110 supplies a gas containing crystal source atoms at a pressure equal to or higher than atmospheric pressure. The pressure maintaining means 112 maintains the gas pressure at the gas-liquid interface where the gas and the liquid are in contact with each other at atmospheric pressure or higher. The heating means 114 heats the container 102 and the substance therein. Examples of the gas supply means 110 include a high-pressure gas supply system such as a high-pressure gas cylinder, piping, and a regulator. An example of the pressure maintaining means 112 is a pressure vessel. Examples of the heating means 114 include an electric heater and a halogen lamp heater.

  The container 102 contains a liquid containing crystal source atoms. In the case where the crystal to be formed is gallium nitride, a sodium flux containing gallium can be exemplified as the liquid stored in the container 102. The flux may be other alkali metal such as potassium or alkaline earth metal instead of sodium.

Since sodium flux generally becomes liquid at a high temperature of 500 ° C. or higher and dissolves gallium as a solute, the container 102 is preferably heat resistant. Further, when the inner surface of the container 201 becomes an elastic wave propagation surface as will be described later, the elastic wave (including sound waves or ultrasonic waves, which is the same in this specification) is transmitted well even at high temperatures. It is preferable to be made of a material having a certain degree of rigidity. Specifically, the container 102 is preferably made of AlN, SiC, graphite, BN, Al ₂ O ₃ , or SiO ₂ . The container 102 may be made of a composite material obtained by combining these materials.

The container 102 has a bell jar shape having a convex shape on the lower side, and an upper part is cylindrical. Since the container 102 has such a shape, a flux in which an amount of raw material necessary for crystal growth is dissolved is stored. The inner surface of the container 102 is a liquid contact surface 104 that comes into contact with a liquid containing a crystal material. The material of the member constituting the liquid contact surface 104 may be different from the material of the container 102, but in order to improve the propagation of elastic waves on the liquid contact surface 104, the liquid contact surface 104 is made of AlN, SiC, It is preferably composed of one or more materials selected from the group consisting of graphite, BN, Al ₂ O ₃ and SiO ₂ .

  The crystal raw material and the flux installed in the container 102 are heated by the heating means 114 to become a liquid 120 in which the crystal raw material and the flux are melted. On the other hand, a gas containing crystal raw material atoms is supplied from the gas supply means 110 to the container 102. The gas supplied to the container 102 is maintained at a pressure equal to or higher than the atmospheric pressure by the pressure maintaining means 112, and gas molecules enter the liquid 120 through the gas-liquid interface of the liquid 120. In such a state, if the seed crystal 116 supported by the support member 118 is disposed in the vicinity of the liquid surface of the liquid 120, the crystal is deposited on the surface of the seed crystal 116, and the crystal grows.

  A ring-shaped piezoelectric body 108 is disposed in contact with the container 102 in a cylindrical portion at the top of the container 102. The piezoelectric body 108 is an example of an elastic wave propagation unit that propagates an elastic wave as a traveling wave to the liquid contact surface 104. An elastic wave is generated by applying an alternating electric field to the piezoelectric body 108, and the elastic wave propagates to the liquid contact surface 104. The elastic wave propagates on the wall surface of the container 102 and reaches the piezoelectric body 108 to form a standing wave. However, the applied strength of the alternating voltage is attenuated during the propagation process, and the piezoelectric body A traveling wave can be obtained by suppressing the level to 108.

  The elastic wave propagates as a traveling wave in the direction indicated by the black arrow (from top to bottom). The elastic wave propagates through the liquid contact surface 104 as a traveling wave, so that the liquid 120 in contact with the liquid contact surface 104 is transported in the traveling direction of the traveling wave. As a result, a flow like a white arrow is generated in the liquid 120, and a sufficient amount of crystal material is supplied to the crystal growth surface of the seed crystal 116. In particular, the nitrogen raw material dissolved in the liquid can be effectively transported to the seed crystal surface from the interface between the solid and the liquid. As a result, the growth rate of the crystal is increased and the quality of the crystal is improved. Moreover, even when parasitic precipitation occurs, the liquid 120 is sufficiently stirred, so that the crystals that have been parasitically precipitated are remelted, and the yield of the raw material can be increased.

The piezoelectric body that is the elastic wave propagation means may be a part of the container 102. Further, the gas supplied by the gas supply means 110 may be directly introduced into the liquid 120. As the piezoelectric material 108, a material having a Curie point of 500 ° C. or higher is selected. For example, the piezoelectric body 108 may be made of one or more materials selected from the group consisting of La ₃ Ga ₅ SiO ₁₄ , LiNbO ₃ , SiO ₂ , AlN, and AlN / Sc.

  In the crystal growth method using the crystal growth apparatus 100 described above, the container 102 contains a liquid containing crystal source atoms and the container 102 while propagating an elastic wave as a traveling wave to the liquid contact surface 104 in contact with the liquid. Contacting a seed crystal of the crystal with the liquid inside and growing the crystal. In the stage of growing a crystal, a gas containing crystal source atoms is supplied to the container 102, and the crystal is grown while maintaining the pressure of the gas at atmospheric pressure or higher. When growing a gallium nitride single crystal as a crystal, a liquid containing gallium atoms and alkali metal atoms is used as the liquid 120, and a gas containing nitrogen atoms is supplied as the gas. Examples of the gas containing nitrogen atoms include nitrogen gas, ammonia gas, and hydrazine gas. As the voltage (amplitude) of the alternating electric field applied to the piezoelectric body 108 is larger and the frequency is higher, the transport speed of the liquid 120 is improved and a good crystal can be formed.

  FIG. 3 is a schematic cross-sectional view of the crystal growth apparatus 200 as viewed from the front. The crystal growth apparatus 200 is the same as the crystal growth apparatus 100 except that the crystal growth apparatus 200 is different from the crystal growth apparatus 100 in that it has a plurality of piezoelectric bodies 108 as elastic wave propagation means. Therefore, only differences from the crystal growth apparatus 100 will be described.

  In the crystal growth apparatus 200, the phase of the alternating electric field applied to each piezoelectric body 108 can be adjusted by using a plurality of piezoelectric bodies 108. By adjusting the phase of the alternating electric field, the directivity of the elastic wave (the traveling direction of the traveling wave of the acoustic wave) can be made the alignment direction of the piezoelectric bodies 108. Thereby, a traveling wave of a larger elastic wave can be generated, and the liquid 120 can flow more effectively.

  FIG. 4 is a schematic view of the crystal growth apparatus 300 as viewed from above. FIG. 5 is a schematic cross-sectional view of the crystal growth apparatus 300 as viewed from the front. The crystal growth apparatus 300 is different from the crystal growth apparatus 100 or the crystal growth apparatus 200 in the arrangement of the piezoelectric material 108. That is, the piezoelectric body 108 in the crystal growth apparatus 300 has a linear shape, and is arranged in contact with the outer wall surface so that the length direction of the piezoelectric body 108 is the vertical direction of the container 102. Two piezoelectric bodies 108 are arranged. By arranging the piezoelectric body 108 in this way, the elastic wave travels in the circumferential direction of the container 102 (in the direction of the black arrow in FIG. 4), and the crystal growth apparatus 100 or the crystal growth apparatus 200 The traveling direction will be different. As a result, the fluid 120 flows in the direction of the white arrow and generates a flow that draws a circle near the crystal growth surface (near the liquid surface of the liquid 120). In the crystal growth apparatus 100 and the crystal growth apparatus 200, the flow of the liquid 120 in the vicinity of the liquid surface near the crystal growth surface is a flow that is ejected from the central portion. As described above, the flow is like drawing a circle on the liquid surface and forms a smoother laminar flow. As a result, the crystal quality can be further improved.

  In the crystal growth apparatus 300, since the piezoelectric body 108 is arranged as described above, when the elastic wave propagates in the liquid contact surface 104 of the container 102 in the circumferential direction, it has a circulation path that goes around once and reaches the original position. In this case, the phase of the alternating electric field applied to the piezoelectric body 108 can be adjusted so that the amplitude of the elastic wave propagated through the circulation path is enhanced. As a result, a traveling wave can be stably and continuously generated without making the elastic wave a standing wave. That is, the energy input as the elastic wave is efficiently converted into a traveling wave, and can contribute to the transport of the liquid 120 without wasting energy.

  In the crystal growth apparatus 300, a plurality of piezoelectric bodies 108 are arranged, and the phase of an alternating electric field applied to each of the plurality of piezoelectric bodies 108 can be adjusted. That is, when two piezoelectric bodies 108 selected from the plurality of piezoelectric bodies 108 are located at a distance L, the phase of the alternating electric field applied to each of the two piezoelectric bodies 108 is different by 90 degrees or 270 degrees. The frequency and phase of the voltage applied to the piezoelectric body 108 are adjusted so that L = λ (n + 1/4), where n is an integer, between the wavelength λ of the elastic wave and the distance L. By adjusting in this way, a large traveling wave can be generated and the liquid 120 can flow more effectively.

  FIG. 6 is a schematic cross-sectional view of the crystal growth apparatus 400 as viewed from the front. The crystal growth apparatus 400 is the same as the crystal growth apparatus 200 except that the crystal growth apparatus 400 is different from the crystal growth apparatus 200 in that it has vibration isolation means 202. Therefore, only different points will be described. The vibration isolation means 202 is located away from the elastic wave propagation means 106. An example of the vibration isolation unit 202 is an elastic wave absorbing member 204 that absorbs an elastic wave that has propagated through the liquid contact surface 104 and reached the vibration isolation unit 202.

  When the vibration isolator 202 is not provided, the elastic wave emitted from the piezoelectric body 108 may be reflected at the bottom of the container 102 and generate a standing wave on the liquid contact surface 104. However, by having the vibration isolation means 202, a reflected wave that causes a standing wave is not generated, and elastic wave energy can be efficiently converted into a traveling wave.

  Note that another configuration as shown in FIG. FIG. 7 is a schematic cross-sectional view of the crystal growth apparatus 500 as viewed from the front. The vibration isolation unit 202 of the crystal growth apparatus 500 is a piezoelectric body 108 that generates vibrations that cancel the elastic waves that have propagated through the liquid contact surface 104 and reached the vibration isolation unit 202. The piezoelectric body 108 as the vibration isolation means 202 is disposed away from the piezoelectric body 108 as the elastic wave propagation means. That is, the piezoelectric body 108 as the vibration isolation unit 202 is disposed near the bottom of the container 102. A voltage that generates a vibration that cancels the elastic wave is applied to the piezoelectric body 108 as the vibration isolation means 202. Thereby, generation | occurrence | production of a standing wave can be prevented. If the vibration isolation means 202 of the crystal growth apparatus 400 is a passive vibration isolation means, it can be said that the vibration isolation means 202 of the crystal growth apparatus 500 is an active vibration isolation means.

  FIG. 8 is a schematic view of the crystal growth apparatus 600 as viewed from above. FIG. 9 is a schematic cross-sectional view of the crystal growth apparatus 600 as viewed from the front. The crystal growth apparatus 600 is intended to give the elastic wave propagation which gives a driving force to the flow of the liquid 120 not only by the container 102 but also by the elastic body 210. The crystal growth apparatus 600 further includes an elastic body 210. The elastic body 210 is installed inside the container 102. In the crystal growth apparatus 600, the elastic body 210 is disposed at the center of the cylindrical shape of the container 102, but it is not necessary to be at the center.

  The elastic body 210 has a cylindrical shape, and a piezoelectric body 218 as an elastic wave propagation unit and a piezoelectric body 218 as a vibration isolation unit 202 are disposed in contact with the inside of the elastic body 210. The material of the elastic body 210 can be the same as that of the container 102.

  By applying an alternating electric field to the piezoelectric body 218 as the elastic wave propagation means, a traveling wave of an elastic wave can be generated on the surface of the elastic body 210. The surface of the elastic body 210 is in contact with the liquid 120, and can function as the liquid contact surface 104 that gives the liquid 120 a driving force for flow. Note that a part of the elastic body 210 may be the piezoelectric body 218. As in the case of the container 102, the piezoelectric body 218 is provided in plural and the phase of the alternating electric field applied to each of the plurality of piezoelectric bodies 218 can be adjusted. In addition, by causing the piezoelectric body 218 as the vibration isolation means 202 to function, the occurrence of standing waves on the surface of the elastic body 210 can be prevented.

  In addition to the driving of the liquid 120 by the elastic wave traveling wave on the inner surface of the container 102, the liquid 120 is driven more strongly by the driving by the elastic wave traveling wave on the surface of the elastic body 210, the fluidity of the liquid 120 is increased, and the growing crystal Therefore, the crystal uniformity can be improved.

  FIG. 10 is a schematic view of the crystal growth apparatus 700 as viewed from above. FIG. 11 is a schematic cross-sectional view of the crystal growth apparatus 700 as viewed from the front. The crystal growth apparatus 700 is an example in which the elastic body 210 is applied to the crystal growth apparatus 300 in which the liquid 120 flows so as to draw a circle in the circumferential direction. In this case, the elastic body 210 has a circular path where the elastic wave propagating on the liquid contact surface 104 reaches the original position, and is applied to the piezoelectric body 218 so that the amplitude of the elastic wave propagated through the circular path is enhanced. The phase of the alternating electric field can be adjusted. Also in the case of the crystal growth apparatus 700, in addition to the driving force from the traveling acoustic wave propagating through the inner surface of the container 102, the driving force of the traveling acoustic wave propagating through the surface of the elastic body 210 is added, and the liquid 120 flows more strongly. To do. As a result, it is possible to improve the quality of the crystal, increase the growth rate, improve the yield, and the like. The piezoelectric body 218 includes a plurality of piezoelectric bodies 218. By adjusting the phase of the alternating electric field applied to each of the plurality of piezoelectric bodies 218, an elastic wave is propagated as a traveling wave, 2 selected from the plurality of piezoelectric bodies 218 Two piezoelectric bodies 218 are located at a distance L, and the phase of the alternating electric field applied to each of the two piezoelectric bodies 218 is 90 degrees or 270 degrees different from each other, between the wavelength λ of the elastic wave and the distance L. In addition, L = λ (n + 1/4), where n may be an integer, is the same as in the case of the container 102.

  FIG. 12 is a schematic view of the crystal growth apparatus 800 as viewed from above. FIG. 13 is a schematic cross-sectional view of the crystal growth apparatus 800 as viewed from the front. In the crystal growth apparatus 800, the container 102 has a barrel shape. Even in the container 102 having such a barrel shape, an acoustic wave traveling wave in the black arrow direction can be generated by the piezoelectric body 108 and the liquid 120 can flow in the white arrow direction. Also in this case, as in the case of the crystal growth apparatus 100 to the crystal growth apparatus 700, the uniformity of the crystal can be improved, and the growth rate can be increased, the crystal quality can be improved, and the yield can be improved. The container 102 of the crystal growth apparatus 800 has a circular path, and the phase of the alternating electric field applied to the piezoelectric body 108 can be adjusted so that the amplitude of the elastic wave propagated through the circular path is enhanced. By adjusting the phase of the alternating electric field applied to each of the plurality of piezoelectric bodies 108, the elastic wave is propagated as a traveling wave, and the two piezoelectric bodies 108 selected from the plurality of piezoelectric bodies 108 have a distance L The phase of the alternating electric field applied to each of the two piezoelectric bodies 108 is 90 degrees or 270 degrees apart, and L = λ (n + 1/4) between the wavelength λ of the elastic wave and the distance L. However, the point that n may have an integer is the same as that of the crystal growth apparatus 300 or the crystal growth apparatus 700.

  DESCRIPTION OF SYMBOLS 100 Crystal growth apparatus, 102 Container, 104 Liquid contact surface, 108,218 Piezoelectric body, 110 Gas supply means, 112 Pressure maintenance means, 114 Heating means, 116 Seed crystal 116, 118 Support member, 120 Liquid, 202 Vibration isolation means, 204 Elastic wave absorbing member, 210 Elastic body.

Claims (23)

A container containing a liquid containing source atoms of crystals;
Elastic wave propagation means for propagating elastic waves as traveling waves to the liquid contact surface in contact with the liquid;
A crystal growth apparatus. The crystal growth apparatus according to claim 1, wherein the liquid contact surface is an inner surface of the container. The elastic wave propagation means has a piezoelectric body arranged in contact with the container,
The crystal growth apparatus according to claim 2, wherein the elastic wave is propagated to the liquid contact surface by applying an alternating electric field to the piezoelectric body. The elastic wave propagation means has a piezoelectric body that is a part of the container,
The crystal growth apparatus according to claim 2, wherein the elastic wave is propagated to the liquid contact surface by applying an alternating electric field to the piezoelectric body. A plurality of the piezoelectric bodies;
The crystal growth apparatus according to claim 3, wherein the elastic wave is propagated as a traveling wave by adjusting a phase of an alternating electric field applied to each of the plurality of piezoelectric bodies. Two piezoelectric bodies selected from the plurality of piezoelectric bodies are located at a distance L,
The phase of the alternating electric field applied to each of the two piezoelectric bodies is 90 degrees or 270 degrees different,
Between the wavelength λ of the elastic wave and the distance L,
L = λ (n + 1/4), where n is an integer,
The crystal growth apparatus according to claim 5, having the relationship: The container has a circular path through which an elastic wave propagating on the liquid contact surface reaches an original position;
The crystal growth according to any one of claims 3 to 6, wherein a phase of the alternating electric field applied to the piezoelectric body is adjusted so that an amplitude of an elastic wave propagating through the circulation path is enhanced. apparatus. An elastic body installed inside the container,
The crystal growth apparatus according to any one of claims 1 to 7, wherein the liquid contact surface is a surface of the elastic body. The elastic wave propagation means has a piezoelectric body disposed in contact with the elastic body,
The crystal growth apparatus according to claim 8, wherein the elastic wave is propagated to the liquid contact surface by applying an alternating electric field to the piezoelectric body. The elastic wave propagation means has a piezoelectric body that is a part of the elastic body,
The crystal growth apparatus according to claim 8, wherein the elastic wave is propagated to the liquid contact surface by applying an alternating electric field to the piezoelectric body. A plurality of the piezoelectric bodies;
The crystal growth apparatus according to claim 9 or 10, wherein the elastic wave is propagated as a traveling wave by adjusting a phase of an alternating electric field applied to each of the plurality of piezoelectric bodies. Two piezoelectric bodies selected from the plurality of piezoelectric bodies are located at a distance L,
The phase of the alternating electric field applied to each of the two piezoelectric bodies is 90 degrees or 270 degrees different,
Between the wavelength λ of the elastic wave and the distance L,
L = λ (n + 1/4), where n is an integer,
The crystal growth apparatus according to claim 11 having the relationship: The elastic body has a circular path where an elastic wave propagating on the liquid contact surface reaches an original position;
The crystal growth according to any one of claims 9 to 12, wherein a phase of the alternating electric field applied to the piezoelectric body is adjusted so that an amplitude of an elastic wave propagating through the circulation path is enhanced. apparatus. Further comprising vibration isolation means positioned away from the elastic wave propagation means,
The crystal growth apparatus according to any one of claims 1 to 13, wherein the vibration isolation unit is an elastic wave absorption member that absorbs an elastic wave that has propagated through the liquid contact surface and reached the vibration isolation unit. . Further comprising vibration isolation means positioned away from the elastic wave propagation means,
14. The crystal growth according to claim 1, wherein the vibration isolation unit is a piezoelectric body that generates a vibration that propagates through the liquid contact surface and cancels an elastic wave that reaches the vibration isolation unit. apparatus. A gas supply means for supplying a gas containing raw material atoms of the crystal at a pressure equal to or higher than atmospheric pressure;
Pressure maintaining means for maintaining the pressure of the gas at the gas-liquid interface at which the gas and the liquid are in contact with each other at an atmospheric pressure or higher;
The crystal growth apparatus according to claim 1, further comprising: The crystal growth apparatus according to any one of claims 1 to 16, further comprising heating means for heating the container. The elastic wave propagation means has a piezoelectric body,
The crystal growth apparatus according to claim 17, wherein the piezoelectric body has a Curie point of 500 ° C. or higher. The crystal growth apparatus according to claim 18, wherein the piezoelectric body is made of one or more materials selected from the group consisting of La ₃ Ga ₅ SiO ₁₄ , LiNbO ₃ , SiO ₂ , AlN, and AlN / Sc. Member constituting the liquid contact surface, AlN, SiC, graphite, BN, any one of _Al 2 _{O 3} and SiO ₂ comprising one or more materials selected from the group consisting of claims 1 to claim 19 The crystal growth apparatus described in 1. Storing a liquid containing crystal source atoms in a container;
Growing a crystal by contacting a seed crystal of the crystal with the liquid in the container while propagating an elastic wave as a traveling wave to a liquid contact surface in contact with the liquid;
A crystal growth method comprising: The crystal growth method according to claim 21, wherein in the step of growing the crystal, a gas containing source atoms of the crystal is supplied to the container, and the crystal is grown while maintaining a pressure of the gas at atmospheric pressure or higher. The liquid contains a gallium atom and an alkali metal atom;
The gas contains a nitrogen atom;
The crystal growth method according to claim 22, wherein a gallium nitride single crystal is grown as the crystal.

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