Thermal field structure, device and method for growing gallium oxide crystal by edge-defined film-fed growth

Abstract

The invention relates to the technical field of integrated circuit semiconductor manufacturing, in particular to a thermal field structure, device and method for growing gallium oxide crystals through an edge-defined film-fed growth mode method.The thermal field structure comprises a first heat preservation barrel, and a crystal growth channel with the rectangular cross section is arranged at the center axis of the first heat preservation barrel; a first airflow channel, a second airflow channel and a third airflow channel which penetrate through the side wall and are communicated with the crystal growth channel are formed in the side wall of the first heat preservation barrel, and the inner diameter of the first airflow channel, the inner diameter of the second airflow channel and the inner diameter of the third airflow channel are sequentially increased; the second airflow channel and the third airflow channel are evenly distributed along the outer diameter of the first heat preservation barrel, and the first airflow channel is located below the second airflow channel and the third airflow channel. According to the upper thermal field structure, the airflow channels with different inner diameters are formed, the mode of improving the thermal field is more flexible, and thermal field distribution in the furnace can be effectively adjusted by controlling opening and closing of the airflow channels.

Description

Technical Field

[0001] The present invention relates to the technical field of integrated circuit semiconductor manufacturing, and in particular to a thermal field structure, device and method for growing gallium oxide crystals by a guided mode method. Background Art

[0002] Gallium oxide single crystal (β-Ga 2 O 3 ) is an ultra-wide bandgap semiconductor material with unique advantages. Its bandgap width is as high as 4.9eV, and its breakdown field strength can reach about 8MV / cm. It is suitable for the preparation of high-voltage and high-power devices and ultraviolet detectors. It is one of the fourth-generation semiconductor materials with the greatest potential for engineering applications. Since gallium oxide raw materials are volatile and the crystal has poor thermal conductivity, the preparation of large-sized gallium oxide single crystals usually adopts the guided mode method.

[0003] Although the guided mode method has successfully achieved the growth of large-sized gallium oxide crystals, it has also brought some new challenges. The existing gallium oxide crystal growth process and its thermal field design still face many problems: 1. Improper temperature gradient control: In single crystal growth, the uniformity of the temperature gradient is crucial. If the temperature gradient is too large or unevenly distributed, it will cause stress concentration during crystal growth, which will in turn cause crystal cracks or melting problems. This may also cause defects in the crystal, such as twins or dislocations; 2. Insufficient thermal field stability: During the growth process, fluctuations in the thermal field will affect the growth quality and consistency of the crystal. If the thermal field is unstable, it is easy to cause thermal stress inside the crystal, affecting the quality of the crystal and causing fluctuations in the growth rate, thereby reducing production efficiency and crystal consistency; 3. The contradiction between thermal field design and crystal size expansion: As the size of gallium oxide single crystals increases, the design of the thermal field becomes more complicated. Large-sized crystals require larger uniform heating areas, but this will increase the difficulty of temperature control, and also require more sophisticated thermal field adjustments to avoid uneven cooling or overheating areas in large-sized crystals.

[0004] In response to the thermal field problem during the shouldering process, the patent "CN115874267 A" improves the flow field form of the insulation chamber by introducing air flow holes, but only considers the temperature field control during the shouldering growth process. The early necking process and the subsequent equal-diameter growth, tailing and cooling processes are not considered. This does not fully consider the entire process of gallium oxide growth. In addition, the patented equipment is complex and the modification cost is high. It is not suitable for large-scale production and manufacturing, and is only limited to single products or customized equipment.

[0005] In view of the above problems, the present invention provides a method for improving the thermal field of gallium oxide crystal growth by the guided mode method, redesigns the structure of the insulation layer, and introduces airflow holes to more flexibly and stably improve the thermal field distribution during the entire growth process. On the one hand, the heat loss during crystal growth is improved by adjusting the opening and closing of the airflow holes in the insulation layer; on the other hand, the introduction of airflow holes can ensure that the crystal grows in an oxidizing atmosphere. This technical solution can effectively improve the quality of gallium oxide single crystal growth. Summary of the invention

[0006] One of the purposes of the present invention is to provide a thermal field structure for growing gallium oxide crystals by a guided mode method, and by providing gas flow channels with different inner diameters, the method of improving the thermal field is more flexible.

[0007] The second object of the present invention is to provide a device of a thermal field structure for growing gallium oxide crystals by a guided mode method, by opening air flow channels with different inner diameters around the insulation layer of the upper thermal field structure, and controlling the heat loss during the growth process by adjusting the opening and closing of the air flow channels of the insulation layer to improve the heat loss during the crystal growth process, which can effectively control the crystal quality during the crystal growth process, and at the same time ensure that the crystal grows in an oxidizing atmosphere, which can effectively reduce the crystal defects of the gallium oxide crystal caused by oxygen deficiency.

[0008] The third object of the present invention is to provide a thermal field method for growing gallium oxide crystals by the guided mode method, which is more flexible in improving the thermal field and can achieve rapid control of multiple processes including seeding - necking - shoulder release - equal diameter growth - pulling and finishing - cooling.

[0009] The solution adopted by the present invention to achieve one of the purposes is: a thermal field structure for growing gallium oxide crystals by a guided mode method, comprising a first insulation barrel, a crystal growth channel with a rectangular cross-section is arranged at the central axis of the first insulation barrel, and the side walls of the first insulation barrel are provided with a first airflow channel, a second airflow channel and a third airflow channel which respectively penetrate the side walls and are connected to the crystal growth channel, the inner diameters of the first airflow channel, the second airflow channel and the third airflow channel increase successively, the second airflow channel and the third airflow channel are evenly distributed along the outer diameter of the first insulation barrel, and the first airflow channel is located below the second airflow channel and the third airflow channel.

[0010] Preferably, the first airflow channel, the second airflow channel and the third airflow channel are respectively arranged on the side walls of the first heat-insulating barrel and transversely penetrate the crystal growth channel and the side walls.

[0011] Preferably, the second airflow channels are multiple and evenly arranged into at least one row that transversely penetrates the narrow side wall of the crystal growth channel; the third airflow channels are multiple and evenly arranged into at least one row that transversely penetrates the wide side wall of the crystal growth channel; and the first airflow holes are multiple and evenly distributed below the second airflow channel and the third airflow channel.

[0012] Preferably, the second air flow channel is arranged in a single row, the number of second air flow channels in each row is 4-6, and the inner diameter is 14-16mm; the third air flow channel is arranged in a single row, the number of third air flow channels in each row is 3-5, and the inner diameter is 28-32mm; the first air flow channel is arranged in two rows, respectively located below the second air flow channel and the third air flow channel, the number of first air flow channels in each row is 1-2, and the inner diameter is 3-5mm.

[0013] Preferably, the first insulation barrel is made of zirconium oxide.

[0014] The solution adopted by the present invention to achieve the second purpose is: a device for growing gallium oxide crystals by a guided mold method, comprising an upper thermal field structure, a lower thermal field structure arranged under the upper thermal field structure, a crucible arranged in the lower thermal field structure, a mold arranged at the center of the crucible, and a pulling mechanism arranged in a crystal growth channel, wherein the upper thermal field structure, the crucible, the lower thermal field structure, the mold and the pulling mechanism are all coaxially arranged, a capillary slit is arranged at the center of the mold, and the capillary slit is connected to the crystal growth channel, the upper thermal field structure is the thermal field structure for growing gallium oxide crystals by a guided mold method as described in any one of claims 1 to 5, and during the growth process of the gallium oxide crystal, the thermal field can be adjusted by opening and closing the first airflow channel, the second airflow channel and the third airflow channel, thereby regulating the crystal growth quality.

[0015] Preferably, the lower thermal field structure includes a second insulation barrel and a heating coil arranged outside the second insulation barrel, the second insulation barrel includes a quartz tube, sand and gravel filled in the quartz tube, and a zirconium ring placed on the sand and gravel, the sand and gravel filling height is lower than the height of the quartz tube, the crucible is arranged at the center of the zirconium ring, and the heating coil, quartz tube, zirconium ring and crucible are coaxially arranged.

[0016] As the hub connecting the upper heat field structure and the lower heat field structure, the zirconium ring not only plays the role of heat field regulation, but also plays a positioning role for the placement of the crucible, ensuring that the crucible is in the center of induction heating. The lower part of the zirconium ring is placed horizontally on sand and gravel, and the outer side cooperates perfectly with the quartz tube, and the inner side cooperates perfectly with the iridium crucible cover. The height of the zirconium ring is slightly higher than the crucible for easy removal, and the upper part of the zirconium ring is level with the quartz tube to ensure the sealing of the furnace.

[0017] Preferably, the crucible and the mold are both made of iridium.

[0018] The iridium crucible also includes a crucible cover, the radius of which is slightly larger than the radius of the crucible, and the crucible cover is provided with a through hole of the same size as the mold for the mold to pass through, so that the seal is intact. The iridium mold is placed in the center of the crucible, and a slit of a certain width is opened in the center of the iridium mold to facilitate the transportation of the melt in the crucible.

[0019] The solution adopted by the present invention to achieve the third purpose is: a method for improving the thermal field of gallium oxide crystals grown by guided mode method, which is implemented by the above device and includes the following steps:

[0020] Gallium oxide is placed in a crucible, a mold is installed, and a gallium oxide seed crystal is installed at the end of the pulling mechanism. The crucible is heated by the lower thermal field structure. After the melt in the crucible is transported to the top of the mold through the capillary slit of the mold, the pulling mechanism with the seed crystal is moved down to the top of the mold to make the seed crystal contact with the melt, completing the process of necking - shouldering - equal diameter growth - tailing - cooling, and finally growing a gallium oxide single crystal. During the process of necking - shouldering - equal diameter growth - tailing, the heating power is controlled to remain unchanged, and only the opening and closing of the first airflow channel, the second airflow channel and the third airflow channel are controlled to adjust the thermal field to help the high-quality growth of the crystal. The gas in the first airflow channel, the second airflow channel and the third airflow channel is consistent with the gas composition in the device.

[0021] Preferably, the specific operation of controlling the heating power to remain unchanged during the process of necking, shouldering, equal diameter growth, and tailing, and controlling the opening and closing of the first airflow channel, the second airflow channel, and the third airflow channel is as follows:

[0022] (1) In the necking stage, all first airflow channels are opened, all second airflow channels and third airflow channels are closed, and the gas flow rate is between 1-5 m / s;

[0023] (2) In the shoulder release stage, all the first air flow channels, the second air flow channels and the third air flow channels are opened, and the gas flow rate is between 5-15 m / s;

[0024] (3) In the equal diameter growth stage, all the first air flow channels, the second air flow channels and the third air flow channels are closed, the heating power is kept constant, and the pulling speed is also kept constant;

[0025] (4) At the end of the pulling process, all first airflow channels are opened, and all second and third airflow channels are closed, with the gas flow rate being between 1 and 5 m / s;

[0026] (5) During the cooling stage, the heating is stopped, and all the first airflow channels, the second airflow channels, and the third airflow channels are opened. The airflow speed is increased from small to large. In the first hour, the airflow rate is maintained at 1-5 m / s. After 1 hour, the airflow rate is increased to 10-20 m / s and maintained for 2-4 hours. Then, the crystals are taken out of all airflow channels and allowed to cool naturally.

[0027] The present invention has the following advantages and beneficial effects:

[0028] The upper heat field structure of the present invention improves the heat field in a more flexible manner by providing air flow channels with different inner diameters, and can effectively adjust the temperature field distribution in the furnace by controlling the opening and closing of the air flow channels.

[0029] The device of the present invention opens airflow channels with different inner diameters on the side wall of the upper thermal field structure, controls the heat loss during the crystal growth process by adjusting the opening and closing of the airflow holes of the thermal insulation layer during the growth process, and can effectively control the crystal quality during the crystal growth process. The device of the present invention can ensure that the crystal grows in an oxidizing atmosphere, and can effectively reduce the crystal defects caused by oxygen deficiency in the gallium oxide crystal. The present invention provides a feasible technical solution for growing high-quality gallium oxide single crystals.

[0030] The method of the present invention can effectively regulate the temperature field distribution during the growth process by controlling the opening and closing of air flow channels with different inner diameters. Compared with the previous method of improving the thermal field conditions in the furnace by adjusting the heating power, the invented method of improving the thermal field is more flexible and can achieve rapid control of multiple processes such as seeding - necking - shouldering - equal diameter growth - pulling and finishing - cooling. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 A schematic diagram of the thermal field structure of a gallium oxide crystal grown by a guided mode method according to an embodiment of the present invention;

[0032] Figure 2 Schematic diagram of the structure of a device for growing gallium oxide crystals using a guided mode method according to Example 2 of the present invention;

[0033] Figure 3 This is a diagram of a gallium oxide single crystal substrate prepared in Example 3 of the present invention;

[0034] Figure 4 This is the XRD pattern of the single crystal substrate prepared in Example 3 of the present invention;

[0035] Figure 5 This is an XRD pattern of a single crystal substrate of another single crystal substrate prepared in Example 3 of the present invention;

[0036] Figure 6 This is a picture of a gallium oxide single crystal substrate prepared in Comparative Example 1;

[0037] In the figure: 1. base; 2. heating coil; 3. sand and gravel; 4. quartz tube; 5. zirconium ring; 6. crucible; 7. crucible cover; 8. mold; 81. capillary slit; 9. gallium oxide crystal; 10. first insulation barrel; 11. air flow channel; 12. seed crystal rod, 13. crystal growth channel; Z1 and K1, first air flow channel; Z2-Z5, second air flow channel; K2-K5, third air flow channel. DETAILED DESCRIPTION

[0038] For a better understanding of the present invention, the following examples are provided to further illustrate the present invention, but the present invention is not limited to the following examples.

[0039] Example 1

[0040] like Figure 1 As shown, a thermal field structure for growing gallium oxide crystals by a guided mode method comprises a first heat-insulating barrel 10, wherein a crystal growth channel 13 with a rectangular cross section is arranged at the central axis of the first heat-insulating barrel 10, and the side walls of the first heat-insulating barrel 10 are provided with first airflow channels Z1 and K1, second airflow channels Z2-Z5 and third airflow channels K2-K5 which respectively penetrate the side walls and are connected to the crystal growth channel 13, the inner diameters of the first airflow channels Z1 and K1, the inner diameters of the second airflow channels Z2-Z5 and the inner diameters of the third airflow channels K2-K5 increase successively, the second airflow channels Z2-Z5 and the third airflow channels K2-K5 are evenly distributed along the outer diameter of the first heat-insulating barrel 10, and the first airflow channels Z1 and K1 are located below the second airflow channels Z2-Z5 and the third airflow channels K2-K5.

[0041] In this embodiment, the first airflow channels Z1 and K1, the second airflow channels Z2-Z5 and the third airflow channels K2-K5 are respectively arranged on the side walls of the first heat preservation barrel 10 and transversely penetrate the crystal growth channel 13 and the side walls.

[0042] In this embodiment, there are multiple second airflow channels Z2-Z5, which are evenly arranged into at least one row that transversely penetrates the narrow side wall of the crystal growth channel 13; there are multiple third airflow channels K2-K5, which are evenly arranged into at least one row that transversely penetrates the wide side wall of the crystal growth channel 13; there are multiple first airflow holes Z1 and K1, which are evenly distributed below the second airflow channels Z2-Z5 and the third airflow channels K2-K5.

[0043] In this embodiment, the second airflow channels Z2-Z5 are arranged in a single row, the number of the second airflow channels Z2-Z5 in each row is 4-6, and the inner diameter is 14-16mm; the third airflow channels K2-K5 are arranged in a single row, the number of the third airflow channels K2-K5 in each row is 3-5, and the inner diameter is 28-32mm; the first airflow channels Z1 and K1 are arranged in two rows, respectively located below the second airflow channels Z2-Z5 and the third airflow channels K2-K5, the number of the first airflow channels Z1 and K1 in each row is 1-2, and the inner diameter is 3-5mm.

[0044] In this embodiment, the first heat preservation barrel 10 is made of zirconium oxide.

[0045] In this embodiment, during the growth process, in order to change the thermal field more conveniently and flexibly, air flow channels 11 are opened around the first heat preservation barrel 10. During the crystal growth process, the air flow channels 11 can be flexibly opened and closed to adjust the heat loss, thereby helping the high-quality growth of the crystal. The air flow channels 11 in the embodiment pass through the four sides of the rectangular crystal growth channel 13, and have 4 third air flow channels K2-K5 with a diameter of 30 mm and 1 first air flow channel K1 with a diameter of 4 mm on the wide side, and 5 second air flow channels Z2-Z5 with a diameter of 15 mm and 1 first air flow channel Z1 with a diameter of 4 mm on the narrow side. The number of opening and closing of the air flow channels 11 in the area can be adjusted in real time to control the thermal field in the furnace, thereby controlling the crystal growth quality.

[0046] Example 2

[0047] like Figure 2 As shown, a device for growing gallium oxide crystals by a guided mold method comprises an upper thermal field structure, a lower thermal field structure arranged under the upper thermal field structure, a crucible 6 arranged in the lower thermal field structure, a mold 8 arranged at the center of the crucible, and a pulling mechanism arranged in a crystal growth channel 13. The upper thermal field structure, the crucible, the lower thermal field structure, the mold and the pulling mechanism are all coaxially arranged. A capillary slit 81 is arranged at the center of the mold, and the capillary slit is connected to the crystal growth channel 13. The upper thermal field structure is the thermal field structure for growing gallium oxide crystals by a guided mold method disclosed in Example 1. During the growth of the gallium oxide crystal, the thermal field can be adjusted by opening and closing the first airflow channels Z1 and K1, the second airflow channels Z2-Z5 and the third airflow channels K2-K5, thereby regulating the crystal growth quality.

[0048] In this embodiment, the lower thermal field structure includes a second insulation barrel and a heating coil 2 arranged outside the second insulation barrel, the second insulation barrel includes a quartz tube 4, sand and gravel 3 filled in the quartz tube 4, and a zirconium ring 5 placed on the sand and gravel 3, the filling height of the sand and gravel 3 is lower than the height of the quartz tube 4, the crucible 6 is arranged at the center position of the zirconium ring 5, and the heating coil 2, quartz tube 4, zirconium ring 5 and crucible 6 are coaxially arranged.

[0049] The zirconium ring 5 serves as a hub connecting the upper thermal field structure and the lower thermal field structure. It not only plays the role of thermal field regulation, but also plays a positioning role for the placement of the crucible 6, ensuring that the crucible 6 is in the center of the induction heating. The lower part of the zirconium ring 5 is horizontally placed on the sandstone 3, and the outer side cooperates perfectly with the quartz tube 4, and the inner side cooperates perfectly with the crucible cover 7. The height of the zirconium ring 5 is slightly higher than the crucible 6 for easy removal, and the upper part of the zirconium ring 5 is level with the quartz tube 4 to ensure the sealing of the furnace.

[0050] In this embodiment, the materials of the crucible 6 and the mold 8 are both iridium.

[0051] The crucible 6 also includes a crucible cover 7, the radius of which is slightly larger than that of the crucible 6, and the crucible cover 7 is provided with a through hole of a size equivalent to that of the mold 8, so that the mold can pass through and the seal is intact. The mold 8 is placed at the center of the crucible 6.

[0052] Specifically, an assembly method of a device for growing gallium oxide crystals by a guided mold method, first fix the position of the base 1 to ensure that it does not slip, the base 1 is in the shape of a solid cylinder, then fix the quartz tube 4 on the base 1, the quartz tube 4 is in the shape of a hollow cylinder, ensure that the quartz tube 4 is concentric with the base 1, then fill the quartz tube 4 with sand and gravel 3, the particles of the sand and gravel 3 are relatively fine, and then the sand and gravel 3 is flattened so that the surface of the sand and gravel 3 is flat and has no bumps, and the filling height of the sand and gravel 3 needs to be lower than the height of the quartz tube 4.

[0053] The heating coil 2 is a device for providing a heat source in the furnace, and plays the role of heating the iridium crucible 6. It is located outside the quartz tube 4 to ensure that the quartz tube 4 and the heating coil 2 are concentric. The material of the heating coil 2 is copper.

[0054] The zirconium ring 5 is placed on the flattened gravel 3, ensuring that the zirconium ring 5 is concentric with the quartz tube 4, and the zirconium ring 5 is flush with the upper part of the quartz tube 4. The zirconium ring 5 is made of zirconium oxide and is in the shape of a hollow cylinder. The zirconium ring 5, the quartz tube 4 and the gravel 3 constitute the second insulation barrel.

[0055] The crucible 6 is placed at the center of the zirconium ring 5, and a mold 8 is embedded at the center of the crucible 6. The mold 8 is in the shape of a rectangular parallelepiped, and a capillary slit 81 is provided at the center of the mold 8 to facilitate the transportation of the gallium oxide melt. Then the crucible cover 7 is placed on the crucible 6 to ensure that the crucible cover 7 is concentric with the zirconium ring 5. The crucible 6, the mold 8, and the crucible cover 7 in the equipment are all made of iridium.

[0056] The first heat preservation barrel 10 is placed on the zirconium ring 5 and the quartz tube 4 to ensure that the first heat preservation barrel 10 is concentric with the quartz tube 4. The first heat preservation barrel 10 has air flow channels around it and a rectangular crystal growth channel 13 at the center. The size of the rectangular parallelepiped is larger than the size of the crystal growth. The material of the first heat preservation barrel 10 is zirconium oxide.

[0057] After the melt in the crucible 6 is transported to the top of the mold 8 through the slit of the iridium mold 8, the seed crystal rod 12 with the seed crystal is moved down to the top of the mold 8 so that the seed crystal contacts the melt to complete the seeding operation, and then the melt is pulled upward to complete the necking - shouldering - equal diameter growth - tailing - cooling and other processes through the thermal field control described in Content 5, and finally a gallium oxide single crystal 9 is grown.

[0058] Example 3

[0059] A method for improving the thermal field of gallium oxide crystals grown by a guided mode method is implemented by using the device, and comprises the following steps:

[0060] Gallium oxide is placed in the crucible 6, the mold 8 is installed, and the gallium oxide seed crystal is installed at the end of the seed crystal rod 12. The crucible 6 is heated by the lower thermal field structure. After the melt in the crucible 6 is transported to the top of the mold 8 through the capillary slit 81 of the mold 8, the seed crystal rod 12 with the seed crystal is moved down to the top of the mold 8 so that the seed crystal contacts the melt, completing the process of necking-shouldering-equal diameter growth-tailing-cooling, and finally growing a gallium oxide single crystal. During the process of necking-shouldering-equal diameter growth-tailing, the heating power is controlled to remain unchanged, and the opening and closing of the air flow channel 11 is controlled to adjust the thermal field to help the high-quality growth of the crystal. The gas in the air flow channel 11 is consistent with the gas composition in the device.

[0061] In this embodiment, the heating power is controlled to remain unchanged during the process of necking, shouldering, equal diameter growth, and tailing, and the specific operations of controlling the opening and closing of the first airflow channel, the second airflow channel, and the third airflow channel are as follows:

[0062] (1) In the necking stage, all first airflow channels are opened, all second airflow channels and third airflow channels are closed, and the gas flow rate is between 1-5 m / s;

[0063] (2) In the shoulder release stage, all the first air flow channels, the second air flow channels and the third air flow channels are opened, and the gas flow rate is between 5-15 m / s;

[0064] (3) In the equal diameter growth stage, all the first air flow channels, the second air flow channels and the third air flow channels are closed, the heating power is kept constant, and the pulling speed is also kept constant;

[0065] (4) At the end of the pulling process, all first airflow channels are opened, and all second and third airflow channels are closed, with the gas flow rate being between 1 and 5 m / s;

[0066] (5) During the cooling stage, the heating is stopped, and all the first airflow channels, the second airflow channels, and the third airflow channels are opened. The airflow speed is increased from small to large. In the first hour, the airflow speed is maintained at 1-5 m / s. After 1 hour, the airflow speed is increased to 10-20 m / s and maintained for 2 hours. Then, the crystals are taken out of all airflow channels and allowed to cool naturally.

[0067] Specifically, in the necking stage, the cross-sectional area of ​​the crystal needs to be as small as possible, and the heat loss of the crystal surface needs to be reduced. The airflow channels Z1 and K1 on both sides of the first heat preservation barrel 10 are opened, and the airflow rate is as small as possible, and the flow rate is between 1-5m / s. The airflow channels K2-K5 and Z2-Z5 on both sides are closed.

[0068] During the shoulder release stage, the cross-sectional area of ​​the crystal needs to be enlarged. At this time, it is necessary to increase the heat loss on the crystal surface, open the air flow channels K1-K5, Z1-Z5, and increase the gas flow rate. In order to avoid the crystal from shifting due to excessive airflow, the air flow rate is between 5-15m / s.

[0069] During the isodiameter growth stage, in order to maintain the stability of the crystal cross section, all air flow channels are closed, the heating power is kept constant, and the pulling speed is also kept constant.

[0070] At the end of the pulling process, the cross section of the crystal needs to be continuously reduced, the air flow channels Z1 and K1 on both sides of the first insulation barrel 10 are opened, and other air flow channels are closed, and the air flow speed is 1-5 m / s.

[0071] During the cooling stage, all air flow channels 11 are opened, and the air flow speed is increased from small to large. In the first hour, the air flow rate is maintained at 1-5 m / s. After 1 hour, the air flow rate is increased to 10-20 m / s and maintained for 2 hours. Then the air flow channel 11 is closed and the crystal is taken out to cool naturally.

[0072] In the stage of necking, shouldering and equal diameter growth, the opening and closing of the air flow channel 11 are changed according to actual needs, and the gas in the air flow channel 11 is consistent with the gas composition in the furnace chamber, which can be carbon dioxide (CO 2 ), argon (Ar) or CO 2 / O 2 mixed gas and other gas components.

[0073] like Figure 3 The figure shows a gallium oxide single crystal substrate for a thermal field improvement method for growing gallium oxide crystals using a guided mode method provided in this embodiment. Figure 3 The airflow holes are reasonably controlled to control the thermal field. The airflow hole control scheme introduced in the present invention optimizes the thermal field of the whole process of gallium oxide crystal growth, and the surface smoothness of the grown gallium oxide crystal is greatly improved. The optimized surface looks more uniform and has fewer particles.

[0074] like Figure 4 FIG. 1 is an XRD graph of a single crystal substrate of a thermal field improvement method for growing gallium oxide crystals by a guided mode method provided in this embodiment. Figure 4 The XRD scanning angle in the image is from 15° to 16.2°, the vertical axis is intensity, and there is a single sharp peak, which appears around ω = 15.6°. The calculated FWHM of the peak is 115.2 arcsec, indicating that the angle difference of the peak width at half the intensity is 115.2 arcsec.

[0075] like Figure 5 FIG. 1 is an XRD graph of a single crystal substrate of a thermal field improvement method for growing gallium oxide crystals by a guided mode method provided in this embodiment. Figure 5 The XRD scan results in the figure show that the FWHM of the crystal is 72 arcsec, and the FWHM after thermal field optimization is 43.2 arcsec smaller than the FWHM before optimization, which means that the peak width of the left figure is relatively narrow, indicating that the measured signal has a higher resolution. The narrow peak width means that the system is more accurate, and the signal is concentrated in a smaller angle range, indicating that higher quality crystals can be obtained after thermal field optimization.

[0076] Comparative Example 1

[0077] The existing method for growing gallium oxide single crystals is generally as follows: the temperature is raised to a temperature slightly higher than the melting point of gallium oxide by an iridium heating element, so that the gallium oxide raw material is completely melted, and the molten gallium oxide is transported to the top of the iridium mold by the capillary siphon effect, and evenly spread at the top until the entire mold surface is covered. Subsequently, the seed crystal rod containing the seed crystal is slowly moved down so that the end of the seed crystal is kept at a height of 3-5 mm from the top of the iridium mold to preheat the seed crystal. After 5 to 10 minutes of preheating, seed crystal inoculation begins. When the seed crystal is fully combined with the molten material at the top of the mold, the seeding stage is entered. In order to prevent defects in the seed crystal from being transmitted to the inside of the crystal, it is necessary to increase the heating power of the iridium heating element to perform necking treatment to ensure the high quality of the crystal. Then, the shoulder expansion growth is carried out by reducing the heating power of the heating element, so that the crystal gradually expands laterally until it covers the entire mold. After that, an isodiameter growth process is carried out. After the crystal growth is completed, the temperature is gradually reduced to room temperature, and the crystal is taken out to finally obtain a gallium oxide single crystal.

[0078] like Figure 6 As shown: the gallium oxide single crystal substrate prepared in this comparative example, Figure 6 The gallium oxide single crystal in the process is obtained by controlling the whole growth process only by changing the heating power. The surface twins and impurities of the gallium oxide single crystal are obvious, the surface is rough, and there are obvious cracks and peeling on the edge of the material. The surface of the material has obvious longitudinal stripes, which is obviously related to the inappropriate thermal field distribution.

[0079] The above is only a preferred embodiment of the present invention, which certainly cannot be used to limit the scope of rights of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and changes can be made without departing from the principle of the present invention, and these improvements and changes are also regarded as the protection scope of the present invention.

Claims

1. A thermal field structure for growing gallium oxide crystals by guided mode method, characterized in that: It includes a first heat-insulating barrel, a crystal growth channel with a rectangular cross-section is arranged at the central axis of the first heat-insulating barrel, the side wall of the first heat-insulating barrel is provided with a first airflow channel, a second airflow channel and a third airflow channel which respectively penetrate the side wall and are connected to the crystal growth channel, the inner diameter of the first airflow channel, the inner diameter of the second airflow channel and the inner diameter of the third airflow channel increase successively, the second airflow channel and the third airflow channel are evenly distributed along the outer diameter of the first heat-insulating barrel, and the first airflow channel is located below the second airflow channel and the third airflow channel.

2. The thermal field structure for growing gallium oxide crystals by the guided mode method according to claim 1, characterized in that: The first airflow channel, the second airflow channel and the third airflow channel are respectively arranged on the side wall of the first heat preservation barrel and transversely penetrate the crystal growth channel and the side wall.

3. The thermal field structure for growing gallium oxide crystals by the guided mode method according to claim 2, characterized in that: There are multiple second airflow channels, which are evenly arranged into at least one row that transversely penetrates the narrow side wall of the crystal growth channel. There are multiple third airflow channels, which are evenly arranged into at least one row that transversely penetrates the wide side wall of the crystal growth channel. There are multiple first airflow holes, which are evenly distributed below the second airflow channel and the third airflow channel.

4. The thermal field structure for growing gallium oxide crystals by the guided mode method according to claim 3, characterized in that: The second air flow channel is arranged in a single row, the number of second air flow channels in each row is 4-6, and the inner diameter is 14-16mm; the third air flow channel is arranged in a single row, the number of third air flow channels in each row is 3-5, and the inner diameter is 28-32mm; the first air flow channel is arranged in two rows, respectively located below the second air flow channel and the third air flow channel, the number of first air flow channels in each row is 1-2, and the inner diameter is 3-5mm.

5. The thermal field structure for growing gallium oxide crystals by the guided mode method according to claim 1, characterized in that: The first heat preservation barrel is made of zirconium oxide.

6. A device for growing gallium oxide crystals by a guided mode method, characterized in that: The invention comprises an upper thermal field structure, a lower thermal field structure arranged under the upper thermal field structure, a crucible arranged in the lower thermal field structure, a mold arranged at the center of the crucible, and a pulling mechanism arranged in a crystal growth channel. The upper thermal field structure, the crucible, the lower thermal field structure, the mold and the pulling mechanism are all coaxially arranged. A capillary slit is arranged at the center of the mold, and the capillary slit is connected to the crystal growth channel. The upper thermal field structure is a thermal field structure for growing gallium oxide crystals by a guided mold method as described in any one of claims 1 to 5. During the growth process of the gallium oxide crystal, the thermal field can be adjusted by opening and closing the first airflow channel, the second airflow channel and the third airflow channel, thereby regulating the crystal growth quality.

7. The device for growing gallium oxide crystals by the guided mode method according to claim 6, characterized in that: The lower thermal field structure includes a second insulation barrel and a heating coil arranged outside the second insulation barrel, the second insulation barrel includes a quartz tube, sand and gravel filled in the quartz tube, and a zirconium ring placed on the sand and gravel, the sand and gravel filling height is lower than the height of the quartz tube, the crucible is arranged at the center of the zirconium ring, and the heating coil, quartz tube, zirconium ring and crucible are arranged coaxially.

8. The device for growing gallium oxide crystals by the guided mode method according to claim 6, characterized in that: The crucible and the mold are both made of iridium.

9. A method for improving the thermal field of gallium oxide crystals grown by guided mode method, characterized in that: The method is implemented by using the device according to any one of claims 6 to 8, comprising the following steps: Gallium oxide is placed in a crucible, a mold is installed, and a gallium oxide seed crystal is installed at the end of the pulling mechanism. The crucible is heated by the lower thermal field structure. After the melt in the crucible is transported to the top of the mold through the capillary slit of the mold, the pulling mechanism with the seed crystal is moved down to the top of the mold to make the seed crystal contact with the melt, completing the process of necking - shouldering - equal diameter growth - tailing - cooling, and finally growing a gallium oxide single crystal. During the process of necking - shouldering - equal diameter growth - tailing, the heating power is controlled to remain unchanged, and the opening and closing of the first airflow channel, the second airflow channel and the third airflow channel are controlled to adjust the thermal field to help the high-quality growth of the crystal. The gas in the first airflow channel, the second airflow channel and the third airflow channel is consistent with the gas composition in the device.

10. The method for improving the thermal field of gallium oxide crystal grown by the guided mode method according to claim 9, characterized in that: The specific operations of controlling the heating power to remain unchanged during the process of necking, shouldering, equal diameter growth, and tailing and controlling the opening and closing of the first airflow channel, the second airflow channel, and the third airflow channel are as follows: (1) In the necking stage, all first airflow channels are opened, all second airflow channels and third airflow channels are closed, and the gas flow rate is between 1-5 m / s; (2) In the shoulder release stage, all the first air flow channels, the second air flow channels and the third air flow channels are opened, and the gas flow rate is between 5-15 m / s; (3) In the equal diameter growth stage, all the first air flow channels, the second air flow channels and the third air flow channels are closed, the heating power is kept constant, and the pulling speed is also kept constant; (4) At the end of the pulling process, all first airflow channels are opened, and all second and third airflow channels are closed, with the gas flow rate being between 1 and 5 m / s; (5) During the cooling stage, the heating is stopped, and all the first airflow channels, the second airflow channels, and the third airflow channels are opened. The airflow speed is increased from small to large. In the first hour, the airflow rate is maintained at 1-5 m / s. After 1 hour, the airflow rate is increased to 10-20 m / s and maintained for 2-4 hours. Then, the crystals are taken out of all airflow channels and allowed to cool naturally.

Images