Gallium oxide single crystal growth method and single crystal growth device

Abstract

The present invention relates to a gallium oxide single crystal growth method and a single crystal growth apparatus, according to one aspect of the present invention, the gallium oxide single crystal growth method comprising the steps of: supplying a gallium oxide raw material into a crucible containing iridium; injecting carbon dioxide to form a predetermined partial pressure of carbon dioxide to suppress the loss of iridium; a step for melting the gallium oxide raw material supplied into the crucible; and a step for producing a gallium oxide single crystal from the melt of the gallium oxide starting material. Thus, loss of iridium metal contained in the iridium crucible can be minimized thermodynamically.

Description

Technical Field

[0001] The present invention relates to a gallium oxide single crystal growth method and a single crystal growth device, and more particularly, to a gallium oxide single crystal growth method for semiconductor substrates and a single crystal growth device suitable for the method. Background Art

[0002] Power semiconductors, which are the main semiconductor components used in power control and power conversion systems, have the characteristics of being able to control high voltage and current, minimize energy loss to provide high efficiency and stability, and are also used for high-frequency power conversion due to their fast switching speeds.

[0003] β-Ga2O3, used as a material for power semiconductors, has a wide band gap of about 4.8 eV and a high breakdown field strength of 8 MV / cm, showing a Baliga figure of merit (FOM) equivalent to about 4 times that of GaN and about 10 times that of 4H-SiC, and has attracted much attention in the field of power semiconductor applications.

[0004] As a method for manufacturing gallium oxide single crystals, solution growth methods such as edge-defined film-fed growth (EFG), Czochralski (CZ), and floating-zone (FZ) can be selected. At this time, since gallium oxide melts at a high temperature of more than 1700°C, an expensive crucible with excellent heat resistance and fire resistance must be used as a heating container.

[0005] Iridium (Ir) crucibles are widely used as heating containers for growing gallium oxide single crystals. Iridium is a very rare precious metal with a content ratio of about 10 ppb (parts per billion) in the earth's crust, and is an expensive material.

[0006] However, in a high temperature environment such as the gallium oxide single crystal manufacturing process, the iridium contained in the iridium crucible may be partially oxidized or iridium may be lost to form a gallium-iridium alloy, etc. Therefore, there is a problem of significantly increasing the production cost of the gallium oxide single crystal.

[0007] Therefore, there is a need for a technique for minimizing the loss of iridium during the growth of gallium oxide single crystals using an iridium crucible.

[0008] On the one hand, the above-mentioned background technology is the technical information that the inventor has in order to derive the present invention or has mastered in the process of deriving the present invention, and is not necessarily the known technology disclosed to the general public before applying for the present invention.

[0009] [Prior art literature]

[0010] [Patent Literature]

[0011] (Patent Document 1) Korean Patent No. 10-2325007 (November 5, 2021)

[0012] (Patent Document 2) Korean Patent No. 10-2546042 (June 16, 2023)

[0013] (Patent Document 3) U.S. Patent No. US11674238 (2023.06.13) Summary of the invention

[0014] Technical issues

[0015] An object of one embodiment of the present invention is to provide a gallium oxide single crystal growth method and a single crystal growth apparatus that minimize the loss of iridium metal contained in an iridium crucible.

[0016] The technical problems to be solved by the present invention are not limited to the technical problems mentioned above, and ordinary technicians in this field can clearly understand other technical problems not mentioned from the following records.

[0017] Technical Solution

[0018] As a technical solution for solving the above-mentioned technical problems, according to one aspect of the present invention, a method for growing a gallium oxide single crystal includes: a step of supplying a gallium oxide raw material into a crucible containing iridium; a step of injecting carbon dioxide to form a predetermined partial pressure of carbon dioxide to suppress the loss of the above-mentioned iridium; a step of melting the above-mentioned gallium oxide raw material supplied into the above-mentioned crucible; and a step of manufacturing a gallium oxide single crystal from the melt of the above-mentioned gallium oxide raw material.

[0019] According to another aspect of the present invention, the preset partial pressure of carbon dioxide may be greater than 40% and less than 60%.

[0020] According to another aspect of the present invention, the step of injecting the carbon dioxide may include the step of injecting the carbon dioxide at a pressure within 2.4 bar.

[0021] According to another aspect of the present invention, the step of injecting the carbon dioxide may include the step of injecting argon.

[0022] According to another aspect of the present invention, the step of injecting the argon gas may include the step of injecting the argon gas at a pressure within 4.5 bar.

[0023] According to another aspect of the present invention, after the single crystal growth method is performed once, the mass of the solid iridium metal contained in the crucible may be more than 99.75% of the mass of the solid iridium metal contained in the crucible before the single crystal growth method is performed once.

[0024] According to another aspect of the present invention, the mass of the manufactured gallium oxide single crystal may be greater than 90% of the mass of the supplied gallium oxide raw material.

[0025] According to another aspect of the present invention, after the single crystal growth method is performed once, the mass of the supplied gallium oxide raw material remaining in the crucible may be less than 10% of the mass of the gallium oxide raw material supplied to the crucible before the single crystal growth method is performed once.

[0026] According to another aspect of the present invention, the step of manufacturing the gallium oxide single crystal may include the step of manufacturing the gallium oxide single crystal from the melt by any one of EFG growth and CZ growth.

[0027] As a technical solution for solving the above-mentioned technical problems, according to another aspect of the present invention, a single crystal growth device includes: a crucible; a heating device for heating the above-mentioned crucible; a cavity for accommodating the above-mentioned crucible; an injection unit for injecting carbon dioxide into the above-mentioned cavity; and a control unit for adjusting the partial pressure of the injected carbon dioxide.

[0028] According to another aspect of the present invention, the control unit may adjust the partial pressure of the injected carbon dioxide so that the partial pressure of the carbon dioxide in the cavity is greater than 40% and less than 60%.

[0029] According to another aspect of the present invention, the injection part may inject the carbon dioxide injected into the cavity at a pressure within 2.4 bar.

[0030] According to another aspect of the present invention, the injection portion may inject the argon gas injected into the cavity at a pressure within 4.5 bar.

[0031] According to another aspect of the present invention, the above-mentioned single crystal growth apparatus may further include a throttle valve.

[0032] According to another aspect of the present invention, the throttle valve can be adjusted so that the pressure of the air in the cavity exceeds 1 bar and is less than 1.4 bar.

[0033] According to another aspect of the present invention, the above-mentioned single crystal growing apparatus may further include a seed crystal lifting device for growing the above-mentioned single crystal.

[0034] According to another aspect of the present invention, the cavity may include a high temperature resistant refractory.

[0035] According to another aspect of the present invention, the main raw material of the crucible may be iridium.

[0036] According to another aspect of the present invention, the single crystal growth apparatus may further include a die inside the crucible, and may further include a slit inside the die communicating with the internal space of the crucible.

[0037] According to another aspect of the present invention, the main material of the mold may be iridium.

[0038] Technical Effects

[0039] According to any one of the technical solutions of the present invention described above, a gallium oxide single crystal growth method and a single crystal growth device include a step of injecting carbon dioxide to form a predetermined carbon dioxide partial pressure to suppress the loss of iridium and a control unit for adjusting the partial pressure of the injected carbon dioxide, thereby minimizing the loss of iridium metal contained in the iridium crucible from a thermodynamic point of view.

[0040] In addition, according to any one of the technical solutions of the present invention, the gallium oxide single crystal growth method and the single crystal growth device further include a throttle valve, thereby thermodynamically improving the growth inhibition phenomenon of the gallium oxide single crystal.

[0041] In addition, according to any one of the technical solutions of the present invention, the gallium oxide single crystal growth method and the single crystal growth device include the steps of melting the gallium oxide raw material supplied into the crucible and manufacturing the gallium oxide single crystal from the melt, so that the ratio of the mass of the manufactured gallium oxide single crystal to the mass of the initially supplied gallium oxide raw material can be increased to more than 90%.

[0042] In addition, according to any one of the technical solutions of the present invention, the gallium oxide single crystal growth method and single crystal growth device have the effect of improving process efficiency and productivity due to the above-mentioned effects, and have economic advantages in terms of cost by preventing the loss of iridium metal.

[0043] The technical effects that can be achieved by the present invention are not limited to the above-mentioned effects, and ordinary technicians in the technical field to which the present invention belongs can clearly understand other effects not mentioned from the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 A schematic diagram for illustrating a single crystal growth apparatus according to an embodiment of the present invention;

[0045] Figure 2 is a flow chart for illustrating a method for growing a gallium oxide single crystal according to an embodiment of the present invention;

[0046] Figure 3 A partially cutaway perspective view for illustrating the internal structure of a crucible according to an embodiment of the present invention;

[0047] Figure 4A perspective view for explaining a step of manufacturing a gallium oxide single crystal according to an embodiment of the present invention;

[0048] Figure 5 The following is a table showing the iridium loss rate of the iridium crucible in each gallium oxide single crystal manufacturing process according to the partial pressure of carbon dioxide in the air.

[0049] Description of Reference Numerals

[0050] 10: Single crystal growth device

[0051] 1000: Control Department

[0052] 1100: Gas Supply Department

[0053] 1121: CO2 valve

[0054] 1122: Carbon dioxide storage container

[0055] 1123: Carbon dioxide pipeline

[0056] 1131: Argon valve

[0057] 1132: Argon storage container

[0058] 1133: Argon pipeline

[0059] 1141: Air valve

[0060] 1143: First air duct

[0061] 1153: Second air duct

[0062] 1200: Injection

[0063] 1201: Mixed gas valve

[0064] 1203: Mixed gas pipeline

[0065] 1300: Cavity

[0066] 1310: Crucible support

[0067] 1400: Crucible

[0068] 1410: Mould

[0069] 1411: Slit

[0070] 1500: Heating device

[0071] 1510: Coil

[0072] 1520: Power Inverter

[0073] 1530: Temperature Control Device

[0074] 1600: Gas pressure regulating device

[0075] 1601: Throttle valve

[0076] 1602: Rotary vane pump

[0077] 1603: Third air duct

[0078] 1700: Seed lifting device

[0079] 1710: Seed support

[0080] 2000: Seedlings

[0081] 3000: Single crystal DETAILED DESCRIPTION

[0082] Embodiments of the present invention are described in detail below with reference to the accompanying drawings so that those skilled in the art can easily implement the present invention. However, the present invention can be implemented in various ways and is not limited to the embodiments described herein. In addition, in order to clearly illustrate the present invention, parts not related to the description are omitted in the drawings, and similar reference numerals are added to similar parts throughout the specification.

[0083] Throughout the specification, when a part is described as being "connected" to other parts, this includes not only the case of "direct connection" but also the case of "indirect connection" with other components or elements in between. In addition, when a part is described as "including" a constituent element, it means that other constituent elements may be further included, rather than excluding other constituent elements, unless there is a special description to the contrary. In addition, when a constituent element is expressed in singular form, unless there is a special clear description, the case of including plural elements is also included.

[0084] The shapes, sizes, proportions, angles, quantities, etc. disclosed in the drawings for describing the embodiments of the present invention are exemplary, and therefore the present invention is not limited to the matters shown in the drawings. In addition, if it is considered that the detailed description of the related known technology may unnecessarily obscure the gist of the present invention when describing the present invention, its detailed description will be omitted.

[0085] When interpreting constituent elements, they are interpreted as including the range of error even if there is no clear description otherwise.

[0086] Although "first", "second", etc. are used to describe various components, these components are not limited by these terms. These terms are only used to distinguish one component from other components. Therefore, the first component mentioned below can also be the second component within the technical concept of the present invention.

[0087] The various features in multiple embodiments of the present invention may be partially or completely combined or combined with each other, and as can be fully understood by ordinary technicians in the field, various linkages and drives can be technically realized, and the various embodiments can be implemented independently of each other or implemented together in an associated relationship.

[0088] On the one hand, the tentative effects that can be expected from the technical features of the present invention that are not specifically mentioned in the description of the present invention are treated as recorded in the description. This embodiment is provided to more completely explain the present invention to ordinary technicians in the field. The contents shown in the figure may be exaggerated compared with the actual implementation method of the invention, and the detailed description of the composition that is judged to be possibly unnecessarily obscuring the gist of the present invention may be omitted or briefly recorded.

[0089] The present invention will be described in detail below with reference to the accompanying drawings.

[0090] Figure 1 FIG. 1 is a schematic diagram for illustrating a single crystal growth apparatus according to an embodiment of the present invention.

[0091] See also Figure 1 According to an embodiment of the present invention, a single crystal growth device 10 includes a crucible 1400, a heating device 1500 for heating the crucible 1400, a cavity 1300 for accommodating the crucible 1400, an injection unit 1200 for injecting carbon dioxide into the cavity 1300, and a control unit 1000 for adjusting the partial pressure of the injected carbon dioxide.

[0092] The crucible 1400 according to one embodiment of the present invention is a heating container that can charge and melt the supplied raw materials and store the generated melt. Therefore, the crucible 1400 can be made of a high heat-resistant and high-refractory material that does not deform or melt even at the melting point of the charged raw materials.

[0093] The main raw material of the crucible 1400 according to one embodiment of the present invention may be iridium. Preferably, the crucible 1400 composed only of iridium may be used.

[0094] The single crystal growth apparatus 10 according to one embodiment of the present invention may further include a mold 1410 inside the crucible 1400 , and may further include a slit communicating with the inner space of the crucible 1400 inside the mold 1410 .

[0095] The slit causes the melt to rise to induce growth into a single crystal, and the cross-sectional shape of the slit may correspond to the cross-sectional shape of the single crystal finally manufactured.

[0096] The mold 1410 forms the outer wall of the slit, and can be formed to have an appropriate thickness to prevent the melt rising to the slit from leaking and evaporating. The main material of the mold 1410 can be iridium.

[0097] The heating device 1500 according to one embodiment of the present invention is a device that can heat the raw material supplied to the crucible 1400 to melt. As the heating device 1500, a resistance heating device, an induction heating device, a laser heating device, an electron beam heating device, an arc heating device, etc. can be used. Depending on the different heating devices, the heating device can be set outside the crucible 1400, or a part or all of the heating device can be set inside the crucible 1400. Preferably, an induction heating device 1500 can be used, and the induction heating device 1500 can be set outside the crucible 1400.

[0098] The heating device 1500 according to one embodiment of the present invention is an induction heating device 1500 , which may include a coil 1510 , a power inverter 1520 , and a temperature adjustment device 1530 .

[0099] The coil 1510 is made of electric wire, and has a shape of winding the electric wire into a cylindrical shape, a toroidal shape, etc., and is an element having inductance. The electric wire constituting the coil 1510 includes a conductor to enable current to flow. In addition, the coil 1510 according to an embodiment of the present invention must stably maintain its performance even in a high-temperature process environment, so a conductor material having heat resistance can be selected and used.

[0100] The power inverter 1520 according to one embodiment of the present invention is an electrical conversion device that converts a direct current (DC) component into an alternating current (AC) component. The power inverter 1520 may convert an external current into an alternating current of a suitable frequency and apply the alternating current to the coil 1510 .

[0101] The temperature adjustment device 1530 according to one embodiment of the present invention is a device capable of adjusting the degree of heating of the metal material surrounded by the coil 1510 by adjusting the current flowing through the coil 1510 .

[0102] The induction heating device 1500 according to one embodiment of the present invention can heat a metal object using electromagnetic induction. Specifically, when external power is supplied to the coil 1510 with an alternating current of a suitable frequency through the power inverter 1520, the magnetic field changes according to the change of the current flowing through the coil 1510, so that an induced electromotive force is generated inside the metal surrounded by the coil 1510, so that eddy currents can flow. At this time, the Joule heating generated by the metal resistance can increase the temperature of the metal.

[0103] According to the above principle, the induction heating device 1500 according to one embodiment of the present invention can increase the temperature of the crucible 1400 by heating the metal contained in the crucible 1400 surrounded by the heating coil 1510 .

[0104] In addition, the temperature adjustment device 1530 according to one embodiment of the present invention can adjust the temperature of the crucible 1400 and the internal environment of the crucible 1400 by controlling the current flowing through the coil 1510. For example, the temperature adjustment device 1530 according to one embodiment of the present invention can maintain the temperature of the internal environment of the crucible 1400 at a higher temperature than the melting point of the raw material loaded into the crucible 1400.

[0105] The chamber 1300 according to an embodiment of the present invention is a container capable of accommodating a high-temperature object, may accommodate the crucible 1400 and the coil 1510 wound around the crucible 1400 , and may include an opening for connecting the coil 1510 to the outside.

[0106] In addition, the cavity 1300 according to an embodiment of the present invention may include a refractory material that is resistant to high temperatures.

[0107] The refractory is a material having heat resistance and chemical stability, and can be included in the cavity 1300 so that the cavity 1300 does not deform or melt even if a high temperature environment is formed in the cavity 1300. The type of refractory is not limited within the range that can prevent the deformation and melting of the cavity 1300. For example, as the refractory, silicon carbide (SiC), zirconium oxide (zirconia, ZrO2, zirconium di oxide), aluminum oxide (alumina, Al2O3, aluminum oxide), silicon nitride (Si3N4, silicon nitride), tungsten (W, tungsten), molybdenum (Mo, molybdenum), etc., which can maintain physical and chemical stability in a high temperature environment, can be used. Preferably, zirconium oxide or aluminum oxide can be used.

[0108] In addition, the chamber 1300 according to one embodiment of the present invention may include a crucible support portion 1310 for supporting and fixing the crucible 1400 .

[0109] The crucible support part 1310 according to one embodiment of the present invention connects and fixes the inner wall of the cavity 1300 and the crucible 1400 to each other, and unnecessary movement of the crucible 1400 and the contents loaded into the crucible 1400 can be minimized during the execution of the process. The specific form of the crucible support part 1310 is not limited within the range that the crucible 1400 can be stably supported and fixed. However, the crucible support part 1310 must not be deformed or melted even in the high temperature environment of the cavity 1300, and therefore, the crucible support part 1310 according to one embodiment of the present invention may include a refractory.

[0110] The chamber 1300 including the above-described refractory and the crucible support part 1310 included in the chamber 1300 may stably store and support the crucible 1400 even in a high temperature environment, and thus a single crystal manufacturing process may be stably performed.

[0111] The cavity 1300 according to an embodiment of the present invention may be formed by a partition wall that blocks the entry and exit of unnecessary substances and energy between the inside and outside of the cavity 1300, except for openings provided for specific purposes such as an opening for connecting the coil 1510 to the outside. Therefore, the temperature inside the cavity 1300, the pressure of the air, the partial pressure of each gas, and other environments can be smoothly controlled.

[0112] The control unit 1000 according to one embodiment of the present invention is a control device that can adjust the partial pressure of carbon dioxide injected into the cavity 1300. In addition, the control unit 1000 according to one embodiment of the present invention can also adjust the partial pressure of various gases injected into the cavity 1300 in addition to carbon dioxide.

[0113] Specifically, the control unit 1000 according to an embodiment of the present invention can adjust the injection pressure of each gas injected into the cavity 1300, and thus can adjust the partial pressure of each gas in the cavity 1300.

[0114] The control unit 1000 according to one embodiment of the present invention may include a mass flow controller (MFC) 1000 .

[0115] The mass flow controller 1000 according to one embodiment of the present invention is a device that can measure and precisely control the gas flow rate, and may include an inlet port, an inner passage, an outlet port, a sensor, a comparator, a control algorithm, an actuator, and a valve. In addition, another gas supply device may be connected to the MFC 1000 so that the MFC 1000 according to one embodiment of the present invention can control the flow rate of the gas flowing into the inner passage, and the connected gas supply device may inject the gas into the inner passage through the valve of the MFC 1000.

[0116] In the case where gas flows into the internal channel through the air intake port of the MFC 1000 according to one embodiment of the present invention, the sensor of the MFC 1000 can measure the flow rate of the gas. The measured flow rate information can be compared with the target flow rate of the gas by the comparator of the MFC 1000. In the case where a difference is found with the target flow rate, the adjustment value of the valve is determined according to the control algorithm of the MFC 1000, and the actuator of the MFC 1000 can adjust the valve according to the determined adjustment value. Thus, the gas can be appropriately injected into the internal channel from the gas supply device connected to the MFC 1000, and the flow rate of the gas flowing into the internal channel can be controlled. The flow-controlled gas can be discharged from the exhaust port of the MFC 1000.

[0117] The single crystal growth apparatus 10 according to one embodiment of the present invention may further include a gas supply part 1100 connected to the control part 1000 .

[0118] The gas supply unit 1100 according to an embodiment of the present invention is a gas supply source capable of supplying required gas to the control unit 1000 , and can function as a gas supply device connected to the MFC 1000 .

[0119] The gas supply unit 1100 according to one embodiment of the present invention may include a first air pipeline 1143, an air valve 1141, a carbon dioxide storage container 1122, a carbon dioxide pipeline 1123, and a carbon dioxide valve 1121. In addition, the gas supply unit 1100 according to one embodiment of the present invention may also include an argon storage container 1132, an argon pipeline 1133, and an argon valve 1131.

[0120] The first air duct 1143 according to one embodiment of the present invention is in communication with the outside and the control unit 1000, and is a duct capable of transmitting external air to the control unit 1000. The air valve 1141 according to one embodiment of the present invention is a valve disposed in the first air duct 1143, and can be used to adjust the air flow rate transmitted through the first air duct 1143.

[0121] The carbon dioxide storage container 1122 according to one embodiment of the present invention is a container capable of stably storing and supplying carbon dioxide. The carbon dioxide pipeline 1123 according to one embodiment of the present invention is a pipeline connected to the carbon dioxide storage container 1122 and the control unit 1000, capable of transmitting the carbon dioxide in the carbon dioxide storage container 1122 to the control unit 1000. The carbon dioxide valve 1121 according to one embodiment of the present invention is a valve provided on the carbon dioxide pipeline 1123, which can be used to adjust the flow rate of carbon dioxide transmitted through the carbon dioxide pipeline 1123.

[0122] The argon storage container 1132 according to one embodiment of the present invention is a container capable of stably storing and supplying argon. The argon pipeline 1133 according to one embodiment of the present invention is a pipeline connected to the argon storage container 1132 and the control unit 1000, capable of transmitting the argon in the argon storage container 1132 to the control unit 1000. The argon valve 1131 according to one embodiment of the present invention is a valve provided on the argon pipeline 1133, which can be used to adjust the flow rate of argon transmitted through the argon pipeline 1133.

[0123] When the gas supply unit 1100 supplies external air, carbon dioxide and argon separately to the control unit 1000, the control unit 1000 according to an embodiment of the present invention can precisely control the flow rate of each gas as above, and can precisely adjust the injection pressure of each gas injected into the cavity 1300 and the partial pressure of each gas in the cavity 1300.

[0124] The gas supplied to the injection part 1200 by the control part 1000 according to an embodiment of the present invention may be a single gas or a mixed gas, but for convenience in this specification, the gas supplied to the injection part 1200 by the control part 1000 is collectively referred to as a mixed gas. Specifically, the mixed gas supplied to the injection part 1200 by the control part 1000 according to an embodiment of the present invention may include at least one of the above-mentioned carbon dioxide, argon gas, and external air.

[0125] The injection part 1200 according to an embodiment of the present invention is a device that connects the control part 1000 and the cavity 1300 to each other, and can inject the mixed gas supplied by the control part 1000 into the cavity 1300 .

[0126] The injection part 1200 according to one embodiment of the present invention may include a mixed gas pipeline 1203 and a mixed gas valve 1201 .

[0127] The mixed gas pipeline 1203 according to one embodiment of the present invention is a pipeline that is connected to the control unit 1000 and the cavity 1300 and can inject the mixed gas supplied by the control unit 1000 into the cavity 1300. The mixed gas valve 1201 according to one embodiment of the present invention is a valve disposed on the mixed gas pipeline 1203 and can be used to adjust the flow rate of the mixed gas transmitted through the mixed gas pipeline 1203.

[0128] The mixed gas supplied by the control unit 1000 according to an embodiment of the present invention can be injected into the cavity 1300 through the injection unit 1200 , so that the injection pressure of each gas constituting the mixed gas and the partial pressure of each gas in the cavity 1300 can be precisely adjusted by the control unit 1000 .

[0129] On the one hand, if Figure 1 As shown, the single crystal growth device 10 according to an embodiment of the present invention may further include a gas pressure regulating device 1600 , and the gas pressure regulating device 1600 may include a throttle valve 1601 , a rotary vane pump 1602 , and a third air pipeline 1603 .

[0130] In this case, the gas supply part 1100 according to one embodiment of the present invention may further include a second air duct 1153 for interconnecting the control part 1000 and the third air duct 1603. The second air duct 1153 according to one embodiment of the present invention is a duct capable of transmitting external air supplied by the control part 1000 to the third air duct 1603.

[0131] The air pressure regulating device 1600 according to one embodiment of the present invention is a device capable of regulating the air pressure in the cavity 1300. Here, the air pressure refers to the total pressure equivalent to the sum of the partial pressures of the gases in the cavity 1300.

[0132] According to one embodiment of the present invention, the third air duct 1603 is connected to the second air duct 1153, the rotary vane pump 1602 and the cavity 1300, and can transmit the external air supplied through the second air duct 1153 and the air in the cavity 1300 to the rotary vane pump 1602 through the throttle valve 1601.

[0133] According to one embodiment of the present invention, the throttle valve 1601 is a valve disposed in the third air duct 1603 and can be used to adjust the flow rate of the above-mentioned air transmitted through the third air duct 1603.

[0134] The rotary vane pump 1602 according to one embodiment of the present invention is a device capable of sucking the above-mentioned air from the third air duct 1603 and discharging it to the outside.

[0135] The air in the cavity 1300 according to an embodiment of the present invention and the external air supplied through the second air duct 1153 can be discharged to the outside by adjusting the flow rate by the throttle valve 1601, so that the air pressure in the cavity 1300 can be precisely controlled by the throttle valve 1601. For example, the throttle valve 1601 according to an embodiment of the present invention can be adjusted so that the air pressure in the cavity 1300 exceeds 1 bar and is less than 1.4 bar.

[0136] On the one hand, if Figure 1 As shown, the single crystal growth device 10 according to an embodiment of the present invention may further include a seed crystal lifting device 1700 for growing a single crystal. The seed crystal lifting device 1700 may include a seed crystal supporting portion 1710 and a power portion for driving the seed crystal supporting portion 1710 .

[0137] The seed is a structure introduced into the melt in the single crystal growth process to start the single crystal growth. When one side of the seed is introduced into the melt, the crystallinity of the seed is transferred to the melt and the melt solidifies to form a single crystal. As the adjacent melt on the single crystal formed as above solidifies as the seed rises, the process of extending the single crystal is repeated, and a single crystal can be manufactured on one side of the seed.

[0138] As described above, since the seed crystal must be introduced into the melt, it may be disposed inside the cavity 1300 according to an embodiment of the present invention.

[0139] The seed crystal lifting device 1700 according to one embodiment of the present invention is a power source capable of controlling the up and down movement of the seed crystal.

[0140] The seed support 1710 according to one embodiment of the present invention is a member that penetrates the partition wall of the cavity 1300 and is arranged to support the seed crystal inside the cavity 1300. The seed support 1710 according to one embodiment of the present invention can stably support the seed crystal, and can prevent the seed crystal from separating, falling into the melt, etc. In addition, the seed support 1710 according to one embodiment of the present invention can transmit the power from the above-mentioned power unit to the seed crystal so that the seed crystal rises or falls under the control of the seed crystal lifting device 1700, and the above-mentioned stability can be maintained despite the movement of the seed crystal.

[0141] See below Figure 2 Another gallium oxide single crystal growth method according to a single crystal growth device of an embodiment of the present invention is described. The gallium oxide single crystal growth method can be used Figure 1 The single crystal growth apparatus 10 shown in the figure performs Figure 2The method for growing gallium oxide single crystals is also referred to Figure 1 .

[0142] Figure 2 FIG. 1 is a flow chart for illustrating a method for growing a gallium oxide single crystal according to an embodiment of the present invention.

[0143] See also Figure 2 According to an embodiment of the present invention, a method for growing a gallium oxide single crystal includes a step S1000 of supplying a gallium oxide raw material into a crucible 1400 containing iridium, a step S2000 of injecting carbon dioxide to form a predetermined carbon dioxide partial pressure to suppress the loss of iridium, a step S3000 of melting the gallium oxide raw material supplied into the crucible 1400, and a step S4000 of manufacturing a gallium oxide single crystal from the melt.

[0144] The step S1000 of supplying the gallium oxide raw material into the crucible 1400 containing iridium according to one embodiment of the present invention is a step of loading the gallium oxide raw material into the crucible 1400 .

[0145] The gallium oxide raw material according to an embodiment of the present invention is a raw material with gallium (III) oxide (Ga 2 O 3 ) as a main raw material, and is a raw material that is melted in the crucible 1400 and made into a gallium oxide single crystal.

[0146] Gallium (III) oxide may be composed of α phase, β phase, γ phase, δ phase or ε phase. Preferably, gallium (III) oxide may be in β phase.

[0147] The gallium oxide raw material and the gallium oxide single crystal according to an embodiment of the present invention may consist of only gallium oxide, or may further contain impurities.

[0148] The form of the gallium oxide raw material according to an embodiment of the present invention and whether it has been pre-processed are not limited within the range that it can be melted by the heating device 1500. For example, the gallium oxide raw material can be in various forms such as sphere, cylinder, regular hexahedron, etc., and can be in an unprocessed powder state or a processed sintered body state.

[0149] According to one embodiment of the present invention, step S2000 of injecting carbon dioxide to form a preset carbon dioxide partial pressure to suppress the loss of iridium is a step of adjusting the partial pressure of carbon dioxide around the crucible 1400 to a preset partial pressure in order to prevent the loss of iridium contained in the crucible 1400. The preset partial pressure of carbon dioxide is a partial pressure of carbon dioxide that creates an environment that suppresses the loss of iridium, which will be described in detail later.

[0150] In the step S2000 of injecting carbon dioxide according to one embodiment of the present invention, carbon dioxide supplied by the control part 1000 according to one embodiment of the present invention may be injected into the cavity 1300 through the injection part 1200 .

[0151] According to an embodiment of the present invention, the step S2000 of injecting carbon dioxide may include the step of injecting carbon dioxide at a pressure within 2.4 bar. For example, the control unit 1000 may adjust the injection pressure of carbon dioxide according to the operation method of the control unit 1000 so that the injection unit 1200 injects carbon dioxide into the cavity 1300 at a pressure within 2.4 bar.

[0152] The step S2000 of injecting carbon dioxide according to an embodiment of the present invention may include a step of injecting argon. For example, the argon supplied by the control unit 1000 according to an embodiment of the present invention may be injected into the cavity 1300 together with the carbon dioxide through the injection unit 1200, and the injection pressure of the argon and the partial pressure of the argon in the cavity 1300 may be precisely adjusted by the control unit 1000.

[0153] According to an embodiment of the present invention, the step of injecting argon gas may include the step of injecting argon gas at a pressure within 4.5 bar. Specifically, the control unit 1000 may adjust the injection pressure of argon gas according to the operation method of the control unit 1000 so that the injection unit 1200 injects argon gas into the cavity 1300 at a pressure within 4.5 bar.

[0154] The above-mentioned preset carbon dioxide partial pressure will be described in detail below.

[0155] Gallium oxide melts at temperatures above 1700°C. Iridium oxidation is more likely to occur in such high-temperature environments than in low-temperature environments. The higher the oxygen partial pressure in the environment, the more active the iridium oxidation tends to be. When iridium oxidation is active, corresponding iridium loss may occur.

[0156] If the oxygen partial pressure decreases under high temperature conditions, gallium (III) oxide may be reduced to gaseous gallium (I) oxide (Ga2O) or liquid gallium (Ga, gallium) due to thermal decomposition reaction, and the generated gallium reacts with iridium to form iridium-gallium alloy, etc., which may cause iridium loss. In addition, the growth of gallium oxide single crystals based on gallium oxide raw materials will also be hindered.

[0157] Therefore, there may be limitations in preventing iridium loss if only adjusting the oxygen partial pressure is used.

[0158] Thermodynamically, when the partial pressure of gallium (I) oxide gas is high, the gallium (III) oxide can be actively reduced to gallium by thermal decomposition, thereby increasing the partial pressure of oxygen. Therefore, the formation of the iridium-gallium alloy and the oxidation of iridium increase, and the loss of iridium also increases greatly. In addition, as described above, the growth of gallium oxide single crystals may be inhibited by the thermal decomposition of gallium (III) oxide. Therefore, it may be necessary to reduce the partial pressure of gallium (I) oxide gas.

[0159] The partial pressure of gallium oxide (I) gas can be reduced by adjusting the partial pressure of carbon dioxide or argon. Therefore, the loss of iridium can be prevented by adjusting the partial pressure of carbon dioxide or argon near iridium through the gallium oxide single crystal growth method and single crystal growth apparatus 10 according to one embodiment of the present invention.

[0160] For example, the partial pressure of carbon dioxide can be adjusted to reduce the partial pressure of gallium oxide (I) gas. To this end, the partial pressure of carbon dioxide suitable for minimizing the loss of iridium can be determined. The partial pressure of carbon dioxide that creates an environment that suppresses the loss of iridium as described above is the above-predetermined partial pressure of carbon dioxide.

[0161] In the step S2000 of injecting carbon dioxide according to an embodiment of the present invention, the preset partial pressure of carbon dioxide may be greater than 40% and less than 60%. In addition, the control unit 1000 according to an embodiment of the present invention may adjust the partial pressure of carbon dioxide injected into the cavity 1300 so that the partial pressure of carbon dioxide in the cavity 1300 is greater than 40% and less than 60%.

[0162] In addition, in the gallium oxide single crystal growth method according to an embodiment of the present invention, the throttle valve 1601 according to an embodiment of the present invention can be adjusted so that the air pressure in the chamber 1300 is greater than 1 bar and less than 1.4 bar. For example, the throttle valve 1601 according to an embodiment of the present invention can precisely control the air pressure in the chamber 1300 to be constant within a range of greater than 1 atm and less than 1.3 atm regardless of the temperature in the chamber 1300.

[0163] This can thermodynamically reduce the partial pressure of the gallium (I) oxide gas. As a result, the loss of iridium can be suppressed, and the phenomenon that the growth of the gallium oxide single crystal is suppressed due to the thermal decomposition of gallium (III) oxide can be improved.

[0164] The step S3000 of melting the gallium oxide raw material supplied to the crucible 1400 according to an embodiment of the present invention is a step of liquefying the gallium oxide raw material charged into the crucible 1400 in a high temperature environment to form a melt.

[0165] According to one embodiment of the present invention, the step S3000 of melting the gallium oxide raw material can be performed by maintaining the internal environment of the crucible 1400 at a temperature higher than the melting point of the gallium oxide raw material. In this case, the heating time can be determined in consideration of the composition, total amount, heat of melting, efficiency of the heating device, etc. of the gallium oxide raw material.

[0166] In step S3000 of melting gallium oxide raw materials according to an embodiment of the present invention, as a method of heating the gallium oxide raw materials, resistance heating, induction heating, laser heating, electron beam heating, arc heating, etc. can be used. Preferably, induction heating can be used. For example, the above-mentioned induction heating device 1500 can be used.

[0167] The step S4000 of manufacturing a gallium oxide single crystal from a melt according to one embodiment of the present invention is a step of growing a gallium oxide single crystal from a melt formed in the step S3000 of melting a gallium oxide raw material.

[0168] According to an embodiment of the present invention, step S4000 of manufacturing a gallium oxide single crystal can be performed by solidifying a melt to manufacture a gallium oxide single crystal. For example, as described above, a seed crystal is introduced into the melt and rises, so that a gallium oxide single crystal formed by solidifying the melt can be grown on one side of the seed crystal.

[0169] The step S4000 of manufacturing a gallium oxide single crystal according to an embodiment of the present invention may include the step of manufacturing a gallium oxide single crystal from a melt by any one of EFG growth and CZ growth.

[0170] As described above, there are EFG, CZ and other crystal growth methods for manufacturing gallium oxide single crystals by solidifying melts. In this specification, a single crystal growth method based on the EFG method is used as an example for illustration. However, the gallium oxide single crystal growth method and the single crystal growth device 10 according to an embodiment of the present invention are not only applicable to the EFG method, but can also be implemented and used in the CZ method.

[0171] Figure 3 A partially cutaway perspective view for illustrating the internal structure of a crucible according to an embodiment of the present invention. Figure 4 The figure is a perspective view for explaining the steps of manufacturing a gallium oxide single crystal according to one embodiment of the present invention.

[0172] See also Figure 3 and Figure 4 , the growth of EFG according to an embodiment of the present invention can be performed as follows: the molten material in the crucible 1400 flows into the slit 1411 in the mold 1410 inside the crucible 1400, rises to the upper end of the slit 1411 through the capillary phenomenon and contacts the bottom of the seed crystal 2000, and as the seed crystal 2000 rises, the molten material grows into a gallium oxide single crystal 3000 having the same crystal plane as the bottom of the seed crystal 2000.

[0173] Here, regarding the contact between seed crystal 2000 and the melt, considering the composition and size of single crystal 3000, the seed crystal 2000 can be configured so that the main surface of single crystal 3000 having target characteristics is parallel to the outer wall of slit 1411 and the bottom surface of seed crystal 2000 is in contact with the melt.

[0174] In addition, during the process of the seed crystal 2000 rising, the rising speed of the seed crystal 2000 can be determined within the range of ensuring stable and efficient production of the single crystal 3000. If the rising speed of the seed crystal 2000 is too fast and exceeds the above range, defects may exist in the finally produced single crystal 3000. If the rising speed of the seed crystal 2000 is too slow and exceeds the above range, the production efficiency of the single crystal 3000 may be reduced.

[0175] For example, if the single crystal 3000 to be finally manufactured is a β-Ga2O3 single crystal 3000, the rising speed of the seed crystal 2000 may be determined within a range of 5 mm / h to 20 mm / h. Preferably, the seed crystal 2000 may be raised at a speed of about 10 mm / h.

[0176] In addition, within the above range of the seed crystal 2000 ascending speed, the seed crystal 2000 ascending speed may be kept constant or may be changed, so that the width of the produced single crystal 3000 can be controlled.

[0177] In addition, during the ascending process of the seed crystal 2000 , the seed crystal lifting device 1700 according to an embodiment of the present invention can keep the direction of the seed crystal 2000 constant, or can change the direction of the seed crystal 2000 to change the orientation of the single crystal 3000 midway.

[0178] The quality of the gallium oxide single crystal 3000 manufactured in the step S4000 of manufacturing the gallium oxide single crystal 3000 according to one embodiment of the present invention may be more than 90% of the quality of the gallium oxide raw material supplied in the step S1000 of supplying the gallium oxide raw material.

[0179] In addition, after the gallium oxide single crystal growth method according to one embodiment of the present invention is performed once, the mass of the gallium oxide raw material remaining in the crucible 1400 may be less than 10% of the mass of all the gallium oxide raw materials supplied to the crucible 1400 in the step S1000 of supplying the gallium oxide raw material.

[0180] Here, in this specification, the ratio of the mass of the produced gallium oxide single crystal 3000 to the mass of the gallium oxide raw material initially supplied as described above is simply referred to as a raw material-crystal conversion rate.

[0181] In step S4000 of manufacturing a gallium oxide single crystal according to an embodiment of the present invention, the melt rises to the upper end of the slit 1411 by capillary action, and the rising melt contacts the seed crystal 2000 or the gallium oxide single crystal 3000 manufactured on one side of the seed crystal 2000, and the viscosity of the melt on the contact surface can be kept constant. Therefore, more than 90% of all the melts formed in step S3000 of melting the gallium oxide raw material can be grown into the gallium oxide single crystal 3000, which can improve the raw material-crystal conversion rate.

[0182] As described above, the gallium oxide single crystal growth method and the single crystal growth apparatus 10 according to one embodiment of the present invention can improve process efficiency and productivity of the gallium oxide single crystal 3000 by improving the raw material-crystal conversion rate.

[0183] In addition, after the gallium oxide single crystal growth method according to one embodiment of the present invention is performed once, the mass of the solid iridium metal contained in the crucible 1400 can be more than 99.75% of the mass of the solid iridium metal contained in the crucible 1400 before the above-mentioned one-time execution. That is, the iridium loss rate of each of the above-mentioned steps can be less than 0.25%.

[0184] The present invention will be described in more detail below using experimental examples to illustrate the effects of the above-mentioned gallium oxide single crystal growth method and single crystal growth apparatus.

[0185] However, the following experimental examples are merely illustrative of the present invention, and the present invention is not limited to the following experimental examples.

[0186] (Experimental Example 1) - Conditions for minimizing iridium loss by adjusting CO2 partial pressure

[0187] In order to compare and evaluate how much the iridium loss rate is reduced by the gallium oxide single crystal growth method and single crystal growth apparatus of the present invention, the carbon dioxide partial pressure conditions shown below were used.

[0188]

Table 1

[0189] distinguish Experimental Example 1-1 Experimental Example 1-2 Experimental Examples 1-3 Experimental Examples 1-4 Experimental Examples 1-5 <![CDATA[Partial pressure of CO2 (%)]]> 40 50 60 70 80

[0190] The iridium loss rate was calculated by measuring the mass change of the iridium crucible used for single crystal growth after single crystal growth was carried out under the above carbon dioxide partial pressure conditions. Specifically, the iridium loss rate was calculated by dividing the iridium loss mass by the total mass of iridium before the above single crystal growth. After actual measurement, the calculated iridium loss rate is shown in the following [Table 2].

[0191]

Table 2

[0192]

[0193] in addition, Figure 5The following is a table showing the iridium loss rate of the iridium crucible in each gallium oxide single crystal manufacturing process according to the partial pressure of carbon dioxide in the air.

[0194] See Table 2 and Figure 5 The actual measurement results show that when the carbon dioxide partial pressure is above 40% and below 60%, the iridium loss rate is suppressed to below 0.25%.

[0195] On the one hand, in Experimental Example 1, it was confirmed that the raw material-crystal conversion rate in the gallium oxide single crystal production process was 90% or more.

[0196] The gallium oxide single crystal growth method and single crystal growth apparatus of the present invention have the effect of thermodynamically minimizing the loss of iridium metal contained in the iridium crucible by precisely adjusting the partial pressure of each gas around the iridium crucible and the pressure of the entire air.

[0197] In addition, the gallium oxide single crystal growth method and single crystal growth apparatus of the present invention have the effect of thermodynamically improving the gallium oxide single crystal growth inhibition phenomenon caused by the thermal decomposition of gallium oxide (III) by precisely adjusting the partial pressure of each gas around the iridium crucible and the pressure of the entire air.

[0198] In addition, the gallium oxide single crystal growth method and single crystal growth apparatus of the present invention have the effect of increasing the raw material-crystal conversion rate to more than 90%.

[0199] In addition, the gallium oxide single crystal growth method and single crystal growth apparatus of the present invention have the effect of improving process efficiency and productivity due to the above-mentioned effects, and have an economic advantage in terms of cost by preventing the loss of iridium metal.

[0200] The above description of the present invention is for illustration purposes, and a person skilled in the art of the present invention will appreciate that the present invention can be easily transformed into other specific forms without changing the technical concept or essential features of the present invention. Therefore, it should be understood that the embodiments described above are exemplary in all aspects and are not intended to be limiting. For example, each component described in a single form may be implemented in a dispersed manner, and similarly, the components described in a dispersed manner may also be implemented in a combined manner.

[0201] The scope of the present invention is shown by the appended claims rather than the detailed description above, and it should be interpreted that all changes or modifications derived from the meaning and scope of the claims and their equivalent concepts are included in the scope of the invention.

Claims

1. A method for growing a gallium oxide single crystal, comprising: The step of supplying a gallium oxide raw material into a crucible containing iridium; A step of injecting carbon dioxide to form a preset carbon dioxide partial pressure to inhibit the loss of iridium; a step of melting the gallium oxide raw material supplied into the crucible; and The step of producing a gallium oxide single crystal from the melt of the gallium oxide raw material. 2 . The gallium oxide single crystal growth method according to claim 1 , wherein the preset carbon dioxide partial pressure is greater than or equal to 40% and less than or equal to 60%. 3 . The gallium oxide single crystal growth method according to claim 1 , wherein the step of injecting the carbon dioxide comprises the step of injecting the carbon dioxide at a pressure within 2.4 bar. 4 . The gallium oxide single crystal growth method according to claim 1 , wherein the step of injecting the carbon dioxide comprises the step of injecting argon. 5 . The gallium oxide single crystal growth method according to claim 4 , wherein the step of injecting the argon gas comprises the step of injecting the argon gas at a pressure within 4.5 bar.

6. The gallium oxide single crystal growth method according to claim 1, wherein after performing the single crystal growth method once, the mass of the solid iridium metal contained in the crucible is 99.75% or more of the mass of the solid iridium metal contained in the crucible before performing the method once. 7 . The gallium oxide single crystal growth method according to claim 1 , wherein the mass of the produced gallium oxide single crystal is 90% or more of the mass of the supplied gallium oxide raw material.

8. The gallium oxide single crystal growth method according to claim 1, wherein after performing the single crystal growth method once, the mass of the supplied gallium oxide raw material remaining in the crucible is less than 10% of the mass of the gallium oxide raw material supplied to the crucible before performing the single crystal growth method once.

9. The gallium oxide single crystal growth method according to claim 1, wherein the step of manufacturing the gallium oxide single crystal comprises the step of manufacturing the gallium oxide single crystal from the melt by any one of edge-defined thin film feed growth and Czochralski growth.

10. A single crystal growth device, comprising: Crucible; a heating device for heating the crucible; a cavity for accommodating the crucible; an injection portion for injecting carbon dioxide into the cavity; as well as A control unit adjusts the partial pressure of the injected carbon dioxide. 11 . The single crystal growth apparatus according to claim 10 , wherein the control unit adjusts the partial pressure of the injected carbon dioxide so that the partial pressure of the carbon dioxide in the chamber is not less than 40% and not more than 60%. 12 . The single crystal growth apparatus according to claim 10 , wherein the injection unit injects the carbon dioxide injected into the chamber at a pressure within 2.4 bar. 13 . The single crystal growth apparatus according to claim 10 , wherein the injection portion injects the argon gas injected into the chamber at a pressure within 4.5 bar.

14. The single crystal growth apparatus according to claim 10, further comprising a throttle valve. 15 . The single crystal growth apparatus according to claim 14 , wherein the throttle valve is adjusted so that the air pressure in the chamber exceeds 1 bar and is less than 1.4 bar. 16 . The single crystal growth apparatus according to claim 10 , further comprising a seed crystal lifting device for growing the single crystal. The single crystal growth apparatus according to claim 10 , wherein the chamber comprises a refractory material resistant to high temperatures.

18. The single crystal growth apparatus according to claim 10, wherein a main raw material of the crucible is iridium.

19. The single crystal growth apparatus according to claim 10, further comprising a mold inside the crucible, The mold further includes a slit on the inner side thereof communicating with the inner space of the crucible.

20. The single crystal growth apparatus according to claim 19, wherein a main material of the mold is iridium.

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