System and method for growing uniform nitride single crystals using flux method

Abstract

The present invention discloses a system and method for growing uniform nitride single crystals using a flux method. The system includes: a single crystal growth unit, a raw material circulation unit, a stirring unit, and a nitrogen supply unit; the single crystal growth unit includes a reaction chamber for reactively growing nitride single crystals, the raw material circulation unit includes a circulation chamber for accommodating the raw materials required for growing nitride single crystals, the reaction chamber and the circulation chamber are interconnected, and the raw materials can circulate between the reaction chamber and the circulation chamber; the stirring unit is at least used to stir the raw materials in the circulation chamber and / or the reaction chamber; the nitrogen supply unit is at least used to provide nitrogen to the circulation chamber and / or the reaction chamber. The present invention utilizes the raw material circulation unit and the stirring unit to circulate and stir the raw materials in the reaction chamber and the circulation chamber, so that the grown nitride single crystals have better uniformity and higher quality.

Description

Technical Field

[0001] The present invention relates to a system for growing gallium nitride bulk single crystals, and in particular to a system and method for growing uniform nitride single crystals using a flux method, belonging to the technical field of single crystal material growth. Background Art

[0002] As one of the core materials of third-generation semiconductors, gallium nitride (GaN) possesses excellent properties, including a wide bandgap, high electron mobility, high breakdown field strength, high thermal conductivity, low dielectric constant, strong radiation resistance, and good chemical stability. GaN is widely used in optical devices and high-power electronic devices, such as light-emitting diodes (LEDs), laser diodes (LDs), and high-power transistors. Currently, there are four main methods for producing GaN single crystal substrates: the high-pressure melt method, the hydride vapor phase epitaxy method, the ammonothermal method, and the flux method.

[0003] As a near-thermodynamic equilibrium growth method, the flux method offers numerous advantages and is currently recognized internationally as a low-cost, high-quality, large-size GaN bulk single crystal growth method. The flux method involves selecting appropriate raw material composition ratios (primarily metallic gallium, metallic sodium, and carbon additives), placing a crucible containing the growth materials and GaN seed crystal in a growth furnace, and then, under a nitrogen atmosphere at a specific growth temperature and pressure, liquid phase epitaxy (LPE) is performed on the GaN seed crystal to produce GaN bulk single crystals of varying thicknesses by controlling the growth time.

[0004] Sodium metal acts as a flux to promote the breaking of the N≡N triple bond of N2 to form nitrogen ions (N 3- ), which causes nitrogen ions to dissolve in the molten gallium, increasing the solubility of nitrogen ions in the molten gallium and promoting the growth rate of gallium nitride single crystals. However, due to the high solubility of nitrogen ions near the liquid surface of the molten gallium melt, the melt in this area is easily supersaturated, causing nucleation and growth in this local area, resulting in an excessively high nucleation rate and a large number of small grains, which is not conducive to the liquid phase epitaxial growth of gallium nitride bulk single crystals by the flux method; carbon can inhibit the formation of polycrystals on the crucible wall, thereby improving the yield of gallium nitride single crystals.

[0005] However, during the growth process of GaN, on the one hand, the quality of the grown GaN is uneven due to the uneven distribution of the growth raw materials (mainly metal Ga, metal Na, carbon additives, etc.) of the GaN melt. On the other hand, Figure 1 As shown, nitrogen ions are unevenly distributed in the molten raw material, resulting in a large amount of nitrogen ions dissolved in the surface area of ​​the molten raw material, and the amount of nitrogen dissolved gradually decreases from the surface of the molten raw material downward, resulting in uneven distribution of nitrogen content in the growth system (molten raw material), which in turn leads to slow growth rate, poor and uneven growth quality of gallium nitride single crystals. Summary of the Invention

[0006] The main purpose of the present invention is to provide a system and method for growing uniform nitride single crystals using a flux method, so as to overcome the deficiencies in the prior art.

[0007] To achieve the aforementioned object of the invention, the technical solutions adopted by the present invention include:

[0008] The embodiment of the present invention provides a system for growing uniform nitride single crystals using a flux method, which includes: a single crystal growth unit, a raw material circulation unit, a stirring unit, and a nitrogen supply unit;

[0009] The single crystal growth unit includes a reaction chamber for reaction growth of nitride single crystals, and the raw material circulation unit includes a circulation chamber for accommodating raw materials required for growing nitride single crystals. The reaction chamber and the circulation chamber are interconnected, and the raw materials can circulate between the reaction chamber and the circulation chamber.

[0010] The stirring unit is at least used to stir the raw materials in the circulation chamber and / or the reaction chamber; the nitrogen supply unit is at least used to provide nitrogen into the circulation chamber and / or the reaction chamber; the stirring unit and the nitrogen supply unit can make the nitrogen ions uniformly distributed in the raw materials and maintain the molar ratio of metal gallium and nitrogen ions in the raw materials within a specified range.

[0011] An embodiment of the present invention further provides a method for growing uniform nitride single crystals using a flux method, comprising:

[0012] Provide a system for growing uniform nitride single crystals using the flux method;

[0013] The raw materials required for growing the nitride single crystal are loaded into the reaction chamber of the single crystal growth unit and the circulation chamber of the raw material circulation unit, and the growth conditions are adjusted to grow the nitride single crystal;

[0014] The raw materials in the circulation chamber and / or the reaction chamber are stirred by a stirring unit, nitrogen is introduced into the raw materials in the circulation chamber and / or the reaction chamber by a nitrogen supply unit, and the raw material circulation unit circulates the raw materials in the reaction chamber and the circulation chamber.

[0015] Compared with the prior art, the present invention has at least the following advantages:

[0016] 1) The present invention provides a system and method for growing uniform nitride single crystals using a flux method. The raw material circulation unit circulates raw materials from the upper middle region and the lower middle region of the growth system (the growth system referred to in the present invention mainly refers to the reaction chamber and the circulation chamber), so that nitrogen ions are evenly distributed in the growth system.

[0017] 2) The present invention provides a system and method for growing uniform nitride single crystals using a flux method. The raw material circulation unit and stirring unit can achieve uniform dissolution of nitrogen ions in the raw materials of the growth system, and ensure that the nitrogen ions are uniformly distributed in the raw materials during the growth process of the nitride single crystal, thereby avoiding the problem of uneven quality of the grown nitride single crystals caused by uneven distribution of raw materials and nitrogen ions.

[0018] 3) The present invention proposes a system and method for growing uniform nitride single crystals using a flux method. During the growth process of the nitride single crystals, a raw material circulation unit and a stirring unit are used to circulate and stir the raw materials in the reaction chamber and the circulation chamber, so that the nitrogen ions in the growth system are evenly distributed and the growth raw materials are evenly mixed, thereby making the grown nitride single crystals more uniform and of higher quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 A schematic diagram of the distribution of nitrogen ions in an existing gallium nitride single crystal growth system and a corresponding curve diagram of the solubility of nitrogen ions in the gallium nitride single crystal growth system and different depths of the molten raw material in the growth system;

[0020] Figure 2 This is a schematic structural diagram of a system for growing uniform nitride single crystals using a flux method provided in Example 1 of the present invention. DETAILED DESCRIPTION

[0021] In view of the shortcomings of the prior art, the inventors of this case, after long-term research and extensive practice, have proposed the technical solution of the present invention. The following will further explain this technical solution, its implementation process and principles.

[0022] The embodiment of the present invention provides a system for growing uniform nitride single crystals using a flux method, which includes: a single crystal growth unit, a raw material circulation unit, a stirring unit, and a nitrogen supply unit;

[0023] The single crystal growth unit includes a reaction chamber for reaction growth of nitride single crystals, and the raw material circulation unit includes a circulation chamber for accommodating raw materials required for growing nitride single crystals. The reaction chamber and the circulation chamber are interconnected, and the raw materials can circulate between the reaction chamber and the circulation chamber.

[0024] The stirring unit is at least used to stir the raw materials in the circulation chamber and / or the reaction chamber; the nitrogen supply unit is at least used to provide nitrogen into the circulation chamber and / or the reaction chamber; the stirring unit and the nitrogen supply unit can make the nitrogen ions uniformly distributed in the raw materials and maintain the molar ratio of metal gallium and nitrogen ions in the raw materials within a specified range.

[0025] Furthermore, the raw material circulation unit further includes at least one first material delivery pipeline and at least one second material delivery pipeline, and the reaction chamber is connected to the circulation chamber via the first material delivery pipeline and the second material delivery pipeline respectively;

[0026] The nozzles at both ends of the first material delivery pipeline are respectively arranged at the bottom of the reaction chamber and the bottom of the circulation chamber, and the first material delivery pipeline is also connected to a pump to transport the raw materials at the bottom of the reaction chamber to the bottom of the circulation chamber;

[0027] The material inlet of the second material delivery pipeline is arranged in the middle and upper part of the sequencing chamber, and the material outlet is arranged in the middle and lower part of the reaction chamber. The raw materials in the circulation chamber can flow into the reaction chamber along the second material delivery pipeline.

[0028] Furthermore, the stirring unit includes a first stirring unit, which includes a first driving mechanism and a stirring paddle. The stirring paddle is arranged in the circulation chamber, and the stirring paddle is transmission-connected to the first driving mechanism and can rotate around its own axis under the drive of the first driving mechanism.

[0029] Furthermore, the stirring paddle is provided with a plurality of holes. When the raw materials are stirred by the stirring paddle, the raw materials can flow in the holes. For example, the holes are provided along the tangential direction of the stirring paddle.

[0030] Furthermore, the first material delivery pipeline is also fixedly connected to the stirring paddle and can rotate together with the stirring paddle.

[0031] Furthermore, the first stirring unit further includes a second driving mechanism, which is in transmission connection with the stirring paddle and is at least used to drive the stirring paddle to reciprocate along its own axis.

[0032] Furthermore, the stirring paddle rotates about its own axis while reciprocating along its own axis.

[0033] Furthermore, the first driving mechanism is a rotational driving mechanism, and the second driving mechanism is a linear driving mechanism.

[0034] Furthermore, the stirring unit also includes a second stirring unit, and the second stirring unit includes a third driving mechanism. The third driving mechanism is coordinated with the reaction chamber and the circulation chamber, and is at least used to drive the reaction chamber and the circulation chamber to rotate, wherein the rotation direction of the reaction chamber and the circulation chamber is the same as or opposite to the direction of rotation of the stirring paddle.

[0035] Furthermore, the third driving mechanism is a rotation driving mechanism.

[0036] Furthermore, a magnetic stirring mechanism is also provided in the circulation chamber.

[0037] Furthermore, the nitrogen supply unit includes a nitrogen supply mechanism and a gas pipeline, and the gas outlet of the gas pipeline extends to the bottom of the circulation chamber.

[0038] Furthermore, the gas supply pipeline is integrated with the stirring paddle, the stirring paddle is connected to the nitrogen supply mechanism, the interior of the stirring paddle has a gas supply channel for conveying nitrogen, one end of the stirring paddle extends to the bottom of the circulation chamber, and an air outlet is provided at the end of the stirring paddle.

[0039] Furthermore, the reaction chamber is arranged in the circulation chamber.

[0040] Furthermore, the reaction chamber and the circulation chamber are arranged in the same container.

[0041] Furthermore, the system also includes a control unit, which is connected to the raw material circulation unit, the stirring unit and the nitrogen supply unit, and the control unit is at least used to adjust the working status of the raw material circulation unit, the stirring unit and the nitrogen supply unit.

[0042] An embodiment of the present invention further provides a method for growing uniform nitride single crystals using a flux method, comprising:

[0043] Provide a system for growing uniform nitride single crystals using the flux method;

[0044] The raw materials required for growing the nitride single crystal are loaded into the reaction chamber of the single crystal growth unit and the circulation chamber of the raw material circulation unit, and the growth conditions are adjusted to grow the nitride single crystal;

[0045] The raw materials in the circulation chamber and / or the reaction chamber are stirred by a stirring unit, nitrogen is introduced into the raw materials in the circulation chamber and / or the reaction chamber by a nitrogen supply unit, and the raw material circulation unit circulates the raw materials in the reaction chamber and the circulation chamber.

[0046] In some more specific embodiments, the method specifically includes:

[0047] A first stirring unit is used to stir the raw materials in the circulation chamber so that the nitrogen ions in the circulation chamber are evenly distributed;

[0048] The raw material at the bottom of the reaction chamber is transported to the bottom of the circulation chamber along the first material delivery pipeline under the drive of the pump, and the raw material in the middle and upper part of the circulation chamber is caused to flow to the middle and lower part of the reaction chamber along the second material delivery pipeline, so that the nitrogen ions in the reaction chamber are evenly distributed;

[0049] Nitrogen is delivered to the bottom of the circulation chamber by a nitrogen supply mechanism and a gas pipeline so that the input nitrogen is fully dissolved in the raw material, thereby maintaining the molar ratio of metal gallium and nitrogen ions in the raw material within a specified range.

[0050] Furthermore, the raw material flow rate of the first material delivery pipeline is 1-100 ml. / min; the pressure value of the nitrogen in the gas delivery pipeline is 3-10 MPa.

[0051] Furthermore, the method specifically includes: using a first driving mechanism to drive the stirring paddle to rotate about its own axis to stir the raw materials in the circulation chamber.

[0052] Furthermore, the method specifically includes: causing the stirring paddle to periodically rotate in a first direction and a second direction in sequence, wherein the first direction and the second direction are opposite directions.

[0053] Furthermore, the rotation speed of the stirring paddle is 1-100 r / h.

[0054] Furthermore, the duration of each cycle is 0.01-1 h.

[0055] Furthermore, the method specifically includes: while the stirring paddle rotates about its own axis, a second driving mechanism drives the stirring paddle to reciprocate along its own axis to stir the raw materials in the circulation chamber.

[0056] Furthermore, the linear motion frequency of the stirring paddle on its own axis is 1-100 times / h, and the displacement length is 1-100 cm.

[0057] Furthermore, the method specifically includes: using a third driving mechanism to drive the reaction chamber and the circulation chamber to periodically rotate along the first direction or the second direction around their own axes, wherein the rotation direction of the reaction chamber and the circulation chamber is the same as or opposite to the rotation direction of the stirring paddle.

[0058] Furthermore, the rotation speed of the reaction chamber and the circulation chamber is 1-100 r / h, and the period of the reaction chamber and the circulation chamber rotating along the first direction or the second direction is 0.01-1h.

[0059] Furthermore, the nitride single crystal includes a gallium nitride single crystal.

[0060] Furthermore, the raw material is a molten raw material.

[0061] Furthermore, the raw materials include metallic gallium, metallic sodium and carbon additives, but are not limited thereto.

[0062] The technical solution, its implementation process and principles will be further explained below with reference to the accompanying drawings and specific embodiments.

[0063] Example 1

[0064] See also Figure 2 A system for growing uniform nitride single crystals using a flux method comprises: a single crystal growth unit, a raw material circulation unit, a stirring unit, a nitrogen supply unit and a control unit. The control unit is connected to the raw material circulation unit, the stirring unit and the nitrogen supply unit, and is used to adjust the working states of the raw material circulation unit, the stirring unit and the nitrogen supply unit. The control unit is not shown in the figure. The control unit may include a PLC controller, etc. The PLC controller may adopt existing equipment known to those skilled in the art, which may be commercially available and is not specifically limited here.

[0065] Specifically, the single crystal growth unit includes a reaction chamber for reactively growing nitride single crystals, the raw material circulation unit includes a circulation chamber for accommodating raw materials required for growing nitride single crystals, the reaction chamber and the circulation chamber are interconnected, and the raw materials can circulate between the reaction chamber and the circulation chamber; the stirring unit is at least used to stir the raw materials in the circulation chamber and / or the reaction chamber; the nitrogen supply unit is at least used to provide nitrogen to the circulation chamber and / or the reaction chamber; the stirring unit and the nitrogen supply unit can make the nitrogen ions evenly distributed in the raw materials, and maintain the molar ratio of metal gallium and nitrogen ions in the raw materials within a specified range.

[0066] Specifically, the single crystal growth unit includes a first container (the first container can be a crucible, etc.) 100, the first container has a reaction chamber 110 for reaction growth of nitride single crystals, the raw material circulation unit includes a second container (the second container can be a crucible, etc.) 200 and two sets of material delivery pipelines, the second container 200 A circulation chamber 210 is provided for accommodating raw materials required for growing nitride single crystals. The first container 100 is arranged in the circulation chamber 210 of the second container 200. The raw materials in the reaction chamber 110 and the circulation chamber 210 circulate between the reaction chamber 110 and the circulation chamber 210 through two groups of material delivery pipelines. The two groups of material delivery pipelines are respectively arranged on both sides of the reaction chamber 110 (of course, the number and position of the material delivery pipelines can also be adjusted according to specific circumstances to achieve a similar degree of uniformity of the raw materials in the reaction chamber 110 and the circulation chamber 210). Each group of material delivery pipelines includes a first material delivery pipeline 310 and a second material delivery pipeline 320. The reaction chamber 110 is connected to the circulation chamber 210 via the first material delivery pipeline 310 and the second material delivery pipeline 320 respectively.

[0067] Specifically, the pipe openings at both ends of the first material delivery pipeline 310 are respectively arranged at the bottom of the reaction chamber 110 and the bottom of the circulation chamber 210, and the first material delivery pipeline 310 is also connected to a pump to transport the raw materials at the bottom of the reaction chamber 110 to the bottom of the circulation chamber 210; one end of the second material delivery pipeline 320 directly passes through the container wall of the first container and is arranged in the reaction chamber 110, and the other end is located in the circulation chamber 210, wherein the end of the second material delivery pipeline 320 located in the reaction chamber 110 serves as a material inlet, and the end located in the circulation chamber 210 serves as a material outlet, and the horizontal position of the material inlet of the second material delivery pipeline 320 is higher than the horizontal position of the material outlet, that is, Figure 2 As shown, the material inlet of the second material delivery pipeline 320 is arranged in the middle and upper part of the sequential chamber 210, and the material outlet is arranged in the middle and lower part of the reaction chamber 110. At this time, according to the principle of the communicating vessel, the raw materials in the middle and upper area of ​​the sequential chamber 210 can be transported to the middle and lower area of ​​the reaction chamber 110 along the second material delivery pipeline 320, thereby realizing the circulation exchange of the raw materials in the middle and upper area and the raw materials in the middle and lower areas in the reaction system composed of the reaction chamber 110 and the sequential chamber 210.

[0068] Specifically, the characteristic of communicating vessels is that when the connected containers are filled with the same liquid, the liquid levels in each container are level. If the container is tilted, the liquid in each container will begin to flow from the end with a high liquid column to the end with a low liquid column until the liquid levels in each container are level, that is, stop flowing and become still. Figure 2 As shown, the raw materials in the middle and upper regions of the circulation chamber 210 flow to the middle and lower regions of the reaction chamber 110 through the second feed pipe 320, thereby realizing the circulation exchange of the raw materials in the middle and upper regions and the raw materials in the middle and lower regions in the reaction system composed of the reaction chamber 110 and the sequential chamber 210, so that the nitrogen ions are evenly distributed in the upper and lower regions of the growth system.

[0069] Specifically, during the growth of GaN single crystals, the molar ratio of metallic gallium to nitrogen ions is known as the V / III ratio. A high V / III ratio promotes island growth of GaN single crystals, while a low V / III ratio results in two-dimensional growth. The dislocation evolution, stress state, incorporated impurities, and growth morphology of GaN single crystals grown under these two growth modes differ. Island growth facilitates the bending and annihilation of dislocations, reducing dislocation density and being crucial for improving material quality. In thin films grown in island form, tensile stress exists in the merged island regions, while compressive stress exists in the separated island regions. A low V / III ratio promotes two-dimensional growth, inhibits the formation of columnar structures, and promotes a flat surface perpendicular to the c-plane. Furthermore, a high V / III ratio promotes island growth, enhancing facet and columnar growth, resulting in a roughened GaN single crystal surface and a high number of hillocks and pits. Therefore, the nitrogen ions are evenly distributed in the growth system (which can be understood as the molten raw material system), which can avoid the problem of slow gallium nitride growth rate caused by the low solubility of nitrogen ions below the liquid surface of the molten raw material; in addition, the nitrogen ions are evenly distributed in the entire molten raw material system, which can ensure that a uniform V / III ratio (that is, the ratio of Ga source to N source) is maintained during the growth process, obtaining consistent gallium nitride growth conditions, and thus obtaining gallium nitride single crystals of uniform quality.

[0070] Specifically, the nitrogen supply unit includes a nitrogen supply mechanism and a gas pipeline, and the gas outlet of the gas pipeline is extended to the bottom of the circulation chamber.

[0071] It should be noted that the reaction chamber and the circulation chamber in this embodiment are respectively located in two containers. Of course, the reaction chamber and the circulation chamber can also be located in the same container.

[0072] Specifically, the stirring unit includes a first stirring unit 400 and a second stirring unit 500, wherein the first stirring unit 400 is used to stir the raw materials in the circulation chamber 210, and the second stirring unit is used to drive the first container 100 and the second container 200 to rotate together, and the rotation directions of the first stirring unit 400 and the second stirring unit 500 are opposite.

[0073] Specifically, the first stirring unit includes a first driving mechanism and a stirring paddle 410, the stirring paddle 410 is arranged in the circulation chamber 210, and the stirring paddle 410 is connected to the first driving mechanism and can rotate around its own axis under the drive of the first driving mechanism; during the rotation of the stirring paddle 410, the raw materials in the circulation chamber 210 are stirred, so that the distribution of the raw materials in the circulation chamber 210 is more uniform (mainly to make the nitrogen ions uniformly distributed in the raw materials in different depth areas, which can be understood as the nitrogen ion content in different areas is the same or similar).

[0074] Specifically, the stirring paddle 410 may include more than two stirring rods (which can be understood as stirring cylinders), and the area where the stirring rod can contact the raw material is distributed with multiple holes running through the stirring rod. During the stirring process, the raw material can flow in the holes (that is, the multiple holes on the stirring rod have a "cutting" effect on the raw material), which makes the molten raw material mixed more fully, thereby making the raw material distribution more even, among which the pore size, distribution shape and distribution density of the holes can be adjusted according to the specific situation.

[0075] Specifically, the first driving mechanism can drive the stirring paddle 410 to rotate periodically in a first direction and a second direction in sequence, wherein the first direction and the second direction are opposite directions, the rotation speed of the stirring paddle is 1-100 r / h, and the time of each cycle is 0.01-1h.

[0076] Specifically, the second stirring unit 500 includes a third driving mechanism and a fixed base or fixed container 510. The first container 100 and the second container 200 are both placed or fixedly arranged on the fixed base or in the fixed container 510. The third driving mechanism is in transmission cooperation with the fixed base or fixed container 510, and drives the fixed base or fixed container 510 to drive the first container 100 and the second container 200 to rotate, wherein the rotation direction of the first container 100 and the second container 200 is opposite to the rotation direction of the stirring paddle 410.

[0077] Specifically, the first drive mechanism and the third drive mechanism can be rotating motors, etc. The first drive mechanism and the third drive mechanism are respectively connected to the control unit and can rotate periodically in the first direction and the second direction under the control of the control unit, that is, the first drive mechanism and the third drive mechanism both rotate periodically, but the rotation directions of the two are opposite.

[0078] Specifically, the forward / reverse rotation of the motors of the first stirring unit 400 and the second stirring unit 500 is controlled by the PLC program, and the reverse / forward rotation of the motors of the first stirring unit 400 and the second stirring unit 500 is controlled by the PLC program, so that the two stirring units can rotate forward and reverse periodically, thereby achieving a better stirring effect and obtaining a more uniform molten growth material.

[0079] Specifically, the coordination of the first stirring unit 400 and the second stirring unit 500 allows for a more uniform distribution of the molten raw materials throughout the growth system. This uniform mixing of the raw materials facilitates thorough mixing of the molten metal raw materials, including gallium and sodium. Since sodium, as a flux, promotes the dissolution of nitrogen ions in the molten raw materials, the evenly distributed sodium allows the nitrogen ions to dissolve evenly in the molten raw materials, resulting in thorough and uniform mixing of the gallium and nitrogen ions. This facilitates obtaining a uniform V / III ratio during the growth of the gallium nitride single crystal, maintaining uniform growth conditions during the growth of the gallium nitride single crystal, and obtaining a bulk gallium nitride single crystal of uniform quality. Furthermore, since the temperature field of the growth system is not completely uniform, stirring the growth system using two stirring units rotating in opposite, periodically changing directions can avoid the problem of inconsistent growth temperatures at different locations within the gallium nitride due to uneven temperature distribution within the growth system, thereby avoiding uneven growth quality of the gallium nitride single crystal, and thereby obtaining higher quality and more uniform gallium nitride single crystals.

[0080] Specifically, the gas supply pipeline is integrated with the stirring paddle 410, the stirring paddle 410 is connected to the nitrogen supply mechanism, and the interior of the stirring paddle has a gas supply channel 411 for conveying nitrogen. One end of the stirring paddle extends to the bottom of the circulation chamber 210, and an air outlet is provided at this end of the stirring paddle.

[0081] Specifically, the first material delivery pipeline 310 is fixedly connected to the stirring paddle 410 of the first stirring unit and can rotate together with the stirring paddle.

[0082] Specifically, the first stirring unit 400 also includes a second driving mechanism, which is transmission-connected to the stirring paddle 410 and is at least used to drive the stirring paddle 410 to reciprocate along its own axis, that is, the second driving mechanism can realize the stirring paddle 410 to reciprocate along its own axis while rotating around its own axis (it can also be understood as up and down reciprocating motion), and the reciprocating motion can be a periodic regular motion; the second driving mechanism is a linear drive motor, and the second driving mechanism is also connected to the control unit and can work under the control of the control unit.

[0083] Specifically, the stirring paddle rotates about its own axis while reciprocating along its own axis, which enhances the stirring effect and can accelerate the exchange of molten raw materials in the reaction chamber and the circulation chamber, improve the exchange efficiency of the raw materials, and make the molten raw materials in the growth system more evenly distributed; in addition, when the raw material liquid level in the reaction chamber is low, the stirring paddle of the first stirring unit can be controlled to move downward.

[0084] Specifically, according to the principle of the liquid displacement method (i.e., Archimedes' law of buoyancy: the buoyancy obtained by an object in a liquid is equal to the weight of the liquid it displaces, i.e., Ffloat = Gdisplace = ρliquid gVdisplace (where F is the buoyancy of the object, G is the gravity of the liquid displaced by the object, ρliquid is the density of the displaced liquid, g is the local acceleration of gravity, and Vdisplace is the volume of the discharged water), the raw materials in the circulation chamber can be replenished into the reaction chamber, thereby avoiding the situation where the raw materials in the reaction chamber are insufficient to cover the single crystal epitaxial growth surface and the growth stops, thereby achieving continuous growth of gallium nitride single crystals.

[0085] Specifically, in order to obtain higher raw material uniformity, a magnetic stirring system can be added to the circulation chamber 210 to increase the uniformity of the raw material stirring in the circulation chamber, so that more uniform raw materials are supplied to the reaction chamber 110 with the seed crystal for the growth of gallium nitride single crystals, thereby obtaining gallium nitride single crystals with good uniformity, high quality and large size.

[0086] Taking the flux method to grow gallium nitride crystal as an example, the following Figure 2 The growth of gallium nitride crystals is performed using a system for growing uniform nitride single crystals using a flux method as shown in FIG. , which may specifically include the following steps:

[0087] A seed crystal for growing a gallium nitride single crystal is placed in the reaction chamber 110, and raw materials for growing the gallium nitride single crystal (e.g., metallic gallium, metallic sodium, and carbon additives) are placed in the reaction chamber 110 and the circulation chamber 210 to grow the gallium nitride single crystal under conditions of 3-10 MPa and approximately 800° C.;

[0088] The first driving mechanism drives the stirring paddle to periodically rotate forward and reverse at a speed of 1-100 r / h, and the second driving mechanism drives the stirring paddle to reciprocate up and down along its own axis to stir the raw materials in the circulation chamber so that the nitrogen ions in the circulation chamber are evenly distributed, wherein the period of the forward and reverse rotation of the stirring paddle is 0.01-1h, the movement frequency of the stirring paddle is 1-100 times / h, and the displacement length is 1-100 cm;

[0089] A third driving mechanism drives the reaction chamber and the circulation chamber to periodically rotate forward and reverse about their own axes, wherein the rotation direction of the reaction chamber and the circulation chamber is opposite to the rotation direction of the stirring paddle, the rotation speed of the reaction chamber and the circulation chamber is 1-100 r / h, and the rotation period is 0.01-1h;

[0090] The raw materials at the bottom of the reaction chamber are pumped along the first delivery pipeline at a flow rate of 1-100 ml / min to the bottom of the circulation chamber, and the raw materials in the middle and upper part of the circulation chamber are flowed along the second delivery pipeline to the middle and lower part of the reaction chamber.

[0091] Nitrogen is delivered to the bottom of the circulation chamber through the gas delivery channel inside the stirring paddle so that the input nitrogen is fully dissolved in the raw material, and the pressure of the nitrogen in the gas delivery channel is always maintained at 3-10Mpa; thereby maintaining the molar ratio of metal gallium and nitrogen ions in the raw material within the specified range.

[0092] Specifically, the distribution of nitrogen ions and the molar ratio of metal gallium to nitrogen ions in the growth system can be detected by separate detection, and the parameters in the system can be adjusted according to the detection results, which will not be elaborated in detail here.

[0093] The present invention proposes a system and method for growing uniform nitride single crystals using a flux method. The raw material circulation unit circulates and exchanges the raw materials in the upper and middle regions with the raw materials in the lower and middle regions within the growth system (the growth system referred to in the present invention mainly comprises a reaction chamber and a circulation chamber), so that nitrogen ions are evenly distributed within the growth system.

[0094] The present invention proposes a system and method for growing uniform nitride single crystals using a flux method. The raw material circulation unit and the stirring unit can achieve uniform dissolution of nitrogen ions in the raw materials of the growth system, and ensure that the distribution of nitrogen ions in the raw materials is uniform and consistent throughout the growth process of the nitride single crystal, thereby avoiding the problem of uneven quality of the grown nitride single crystals due to uneven distribution of raw materials and nitrogen ions.

[0095] The present invention proposes a system and method for growing uniform nitride single crystals using a flux method. During the growth process of the nitride single crystal, a raw material circulation unit and a stirring unit are used to circulate and stir the raw materials in the reaction chamber and the circulation chamber, so that the nitrogen ions in the growth system are evenly distributed and the growth raw materials are evenly mixed, thereby making the grown nitride single crystals more uniform and of higher quality.

[0096] It should be understood that the above embodiments are merely illustrative of the technical concepts and features of the present invention. Their purpose is to enable those skilled in the art to understand the contents of the present invention and implement them accordingly. They are not intended to limit the scope of protection of the present invention. Any equivalent variations or modifications made in accordance with the spirit and substance of the present invention are intended to be encompassed within the scope of protection of the present invention.

Claims

1. A system for growing uniform nitride single crystals using a flux method, characterized in that include: Single crystal growth unit, raw material circulation unit, stirring unit and nitrogen supply unit; The single crystal growth unit includes a reaction chamber for reaction growth of nitride single crystals, and the raw material circulation unit includes a circulation chamber for accommodating raw materials required for growing nitride single crystals. The reaction chamber and the circulation chamber are interconnected, and the raw materials can circulate between the reaction chamber and the circulation chamber. The stirring unit is at least used to stir the raw materials in the circulation chamber and / or the reaction chamber; The nitrogen supply unit is at least used to provide nitrogen into the circulation chamber and / or the reaction chamber; the stirring unit and the nitrogen supply unit are capable of uniformly distributing nitrogen ions in the raw material and maintaining the molar ratio of metal gallium to nitrogen ions in the raw material within a specified range; The raw material circulation unit further includes at least one first material delivery pipeline and at least one second material delivery pipeline, and the reaction chamber is connected to the circulation chamber through the first material delivery pipeline and the second material delivery pipeline respectively; The nozzles at both ends of the first material delivery pipeline are respectively arranged at the bottom of the reaction chamber and the bottom of the circulation chamber, and the first material delivery pipeline is also connected to a pump to transport the raw materials at the bottom of the reaction chamber to the bottom of the circulation chamber; The material inlet of the second material delivery pipeline is arranged at the middle and upper part of the sequencing chamber, and the material outlet is arranged at the middle and lower part of the reaction chamber. The raw materials in the circulation chamber can flow into the reaction chamber along the second material delivery pipeline. The stirring unit includes a first stirring unit, which includes a first driving mechanism and a stirring paddle. The stirring paddle is arranged in the circulation chamber, and the stirring paddle is transmission-connected to the first driving mechanism and can rotate around its own axis under the drive of the first driving mechanism; a plurality of holes are also provided on the stirring paddle, and when the raw materials are stirred by the stirring paddle, the raw materials can flow in the holes; the first feed pipeline is also fixedly connected to the stirring paddle and can rotate with the stirring paddle.

2. The system according to claim 1, wherein: The first stirring unit further includes a second driving mechanism, which is in transmission connection with the stirring paddle and is at least used to drive the stirring paddle to reciprocate along its own axis.

3. The system according to claim 2, characterized in that: The stirring paddle reciprocates along its own axis while rotating about its own axis.

4. The system according to claim 2, wherein: The first driving mechanism is a rotary driving mechanism, and the second driving mechanism is a linear driving mechanism.

5. The system according to claim 1, wherein: The stirring unit also includes a second stirring unit, which includes a third driving mechanism. The third driving mechanism is in transmission cooperation with the reaction chamber and the circulation chamber, and is at least used to drive the reaction chamber and the circulation chamber to rotate, wherein the rotation direction of the reaction chamber and the circulation chamber is the same as or opposite to the rotation direction of the stirring paddle; and / or, a magnetic stirring mechanism is also provided in the circulation chamber.

6. The system according to claim 5, characterized in that: The third driving mechanism is a rotation driving mechanism.

7. The system according to claim 1, wherein: The nitrogen supply unit includes a nitrogen supply mechanism and a gas pipeline, wherein the gas outlet of the gas pipeline extends to the bottom of the circulation chamber; and / or, the reaction chamber is disposed in the circulation chamber; And / or, the system further comprises a control unit, which is connected to the raw material circulation unit, the stirring unit and the nitrogen supply unit, and the control unit is at least used to adjust the working states of the raw material circulation unit, the stirring unit and the nitrogen supply unit.

8. The system according to claim 7, characterized in that: The gas supply pipeline is integrated with the stirring paddle, the stirring paddle is connected to the nitrogen supply mechanism, the interior of the stirring paddle has a gas supply channel for conveying nitrogen, one end of the stirring paddle extends to the bottom of the circulation chamber, and an air outlet is provided at the end of the stirring paddle.

9. The system according to claim 7, characterized in that: The reaction chamber and the circulation chamber are arranged in the same container.

10. A method for growing uniform nitride single crystals using a flux method, characterized in that include: Provided is a system for growing uniform nitride single crystals using a flux method according to any one of claims 1 to 9; The raw materials required for growing the nitride single crystal are loaded into the reaction chamber of the single crystal growth unit and the circulation chamber of the raw material circulation unit, and the growth conditions are adjusted to grow the nitride single crystal; The raw materials in the circulation chamber and / or the reaction chamber are stirred by a stirring unit, nitrogen is introduced into the raw materials in the circulation chamber and / or the reaction chamber by a nitrogen supply unit, and the raw material circulation unit circulates the raw materials in the reaction chamber and the circulation chamber.

11. The method according to claim 10, characterized in that Specifically include: A first stirring unit is used to stir the raw materials in the circulation chamber so that the nitrogen ions in the circulation chamber are evenly distributed; The raw material at the bottom of the reaction chamber is transported to the bottom of the circulation chamber along the first material delivery pipeline under the drive of the pump, and the raw material in the middle and upper part of the circulation chamber is caused to flow to the middle and lower part of the reaction chamber along the second material delivery pipeline, so that the nitrogen ions in the reaction chamber are evenly distributed; Nitrogen is delivered to the bottom of the circulation chamber by a nitrogen supply mechanism and a gas pipeline so that the input nitrogen is fully dissolved in the raw material, thereby maintaining the molar ratio of metal gallium and nitrogen ions in the raw material within a specified range.

12. The method according to claim 11, wherein: The raw material delivery flow rate of the first material delivery pipeline is 1-100 mL / min; the pressure value of the nitrogen in the gas delivery pipeline is 3-10 MPa.

13. The method according to claim 11, characterized in that Specifically include: The first driving mechanism drives the stirring blade to rotate about its own axis to stir the raw materials in the circulation chamber.

14. The method according to claim 13, characterized in that Specifically include: The stirring paddle is periodically rotated in a first direction and a second direction in sequence, wherein the first direction and the second direction are opposite directions.

15. The method according to claim 13, wherein: The rotation speed of the stirring paddle is 1-100 r / h.

16. The method according to claim 15, characterized in that: The duration of each cycle is 1-0.01h.

17. The method according to claim 13, characterized in that Specifically include: While the stirring paddle rotates around its own axis, the second driving mechanism drives the stirring paddle to reciprocate along its own axis to stir the raw materials in the circulation chamber.

18. The method according to claim 17, wherein: The linear motion frequency of the stirring paddle on its own axis is 1-100 times / h, and the displacement length is 1-100 cm.

19. The method according to claim 13, characterized in that Specifically include: The reaction chamber and the circulation chamber are driven by a third driving mechanism to rotate together about their own axes in a first direction or a second direction, wherein the rotation direction of the reaction chamber and the circulation chamber is the same as or opposite to the rotation direction of the stirring paddle.

20. The method according to claim 19, wherein: The rotation speed of the reaction chamber and the circulation chamber is 1-100 r / h.

21. The method according to claim 10, wherein: The nitride single crystal includes a gallium nitride single crystal.

22. The method according to claim 21, characterized in that: The raw material is a molten raw material.

23. The method according to claim 21, wherein: The raw materials include metallic gallium, metallic sodium and carbon additives.

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