Double-temperature-zone vertical gallium oxide growth furnace

Abstract

The utility model discloses a double-temperature-zone vertical gallium oxide growth furnace, which relates to the field of semiconductor material epitaxial growth equipment and comprises a furnace body, a gas flow control system and a pressure dynamic control system. The furnace body comprises a furnace tube, an upper temperature area arranged at the upper part of the furnace tube, a lower temperature area arranged at the lower part of the furnace tube and a high-temperature reaction chamber arranged in the middle of the furnace tube; the gas flow control system comprises a multi-path flow meter as well as first gas and second gas which are respectively connected with the multi-path flow meter; and the pressure dynamic control system comprises a vacuum flow meter and a vacuumizing pump connected with the furnace tube through a second pipeline. According to the utility model, gallium oxide rapid epitaxy can be effectively realized.

Description

Technical Field

[0001] The utility model relates to the field of semiconductor material epitaxial growth equipment, and particularly relates to a double-temperature-zone vertical gallium oxide growth furnace. Background Art

[0002] β-Ga2O3 is a wide-bandgap semiconductor material with advantages such as high breakdown field strength, excellent thermal stability, and optical transparency. Therefore, it has broad application potential in the fields of power electronic devices, deep ultraviolet detectors, and high-power devices.

[0003] However, there are some deficiencies in the existing gallium oxide epitaxial growth methods, such as the problem of slow growth rate. Traditional epitaxial growth methods, such as chemical vapor deposition (CVD) and molecular beam epitaxy (MBE), usually require high growth temperatures and it is difficult to control the defect density of crystals. Summary of the Utility Model

[0004] The technical problem to be solved by the utility model is to provide a double-temperature-zone vertical gallium oxide growth furnace. The new device has a clever structure, combines multiple systems, is structurally compact, saves space, is easy to operate, and the combined growth method is convenient and inexpensive, which can well realize the rapid epitaxy of gallium oxide and contribute to the research on the growth of gallium oxide thin films.

[0005] In order to solve the above technical problems, the technical solution of the utility model is as follows:

[0006] The purpose of the utility model is to provide a double-temperature-zone vertical gallium oxide growth furnace.

[0007] The double-temperature-zone vertical gallium oxide growth furnace described in the utility model includes a furnace body, a gas flow control system, and a pressure dynamic control system;

[0008] The furnace body includes a furnace tube, an upper temperature zone arranged at the upper part of the furnace tube, a lower temperature zone arranged at the lower part of the furnace tube, and a high-temperature reaction chamber arranged in the middle of the furnace tube; in the actual use process, the high-temperature reaction chamber can be placed in the furnace tube through a bracket;

[0009] The gas flow control system includes a multi-channel flowmeter and a first gas and a second gas respectively connected to the multi-channel flowmeter. The multi-channel flowmeter is connected to the upper end opening of the furnace tube through a first pipeline, and a first control valve is installed on the first pipeline;

[0010] The pressure dynamic control system includes a vacuum flowmeter and a vacuum pump connected to the furnace tube through a second pipeline. The vacuum flowmeter is connected to the lower end opening of the furnace tube, and a second control valve is installed on the second pipeline.

[0011] In a preferred embodiment of the utility model:

[0012] The upper temperature zone includes heatable molybdenum disilicide rods arranged circumferentially on the upper part of the furnace tube. Preferably, the number of the heatable molybdenum disilicide rods is 8 - 12.

[0013] In a preferred embodiment of the present utility model:

[0014] The lower temperature zone includes heatable molybdenum disilicide rods arranged circumferentially on the lower part of the furnace tube. Preferably, the number of the heatable molybdenum disilicide rods is 8 - 12. The temperatures of the upper and lower temperature zones can be adjusted independently.

[0015] In a preferred embodiment of the present utility model:

[0016] A heat insulation layer is arranged on the outer periphery of the furnace tube. Preferably, the heat insulation layer is aluminosilicate fiber and / or silicon fiber.

[0017] In a preferred embodiment of the present utility model:

[0018] Heat insulation furnace plugs are respectively arranged at the openings at the upper and lower ends of the furnace tube.

[0019] In a preferred embodiment of the present utility model:

[0020] A temperature detection device is arranged in the middle of the furnace tube. Preferably, the temperature detection device is a platinum-rhodium thermocouple and / or an infrared thermometer.

[0021] In a preferred embodiment of the present utility model:

[0022] The first control valve is a vacuum valve; and / or,

[0023] The first gas is argon; and / or,

[0024] The second gas is oxygen; and / or,

[0025] Vacuum valves are respectively installed on the pipelines connecting the first gas and the second gas to the multi-channel flowmeter; and / or,

[0026] The second control valve is a vacuum valve.

[0027] In a preferred embodiment of the present utility model:

[0028] The high-temperature reaction chamber is an alumina crucible; and / or,

[0029] The high-temperature reaction chamber includes a crucible body and an end cover. Preferably, a groove for placing a substrate is formed on the end cover. Thereby, the airtightness during the growth process of the gallium oxide epitaxial layer is ensured.

[0030] In a preferred embodiment of the present utility model:

[0031] The upper end opening of the furnace tube is connected to the first pipeline through the upper stainless steel flange, and the lower end opening of the furnace tube is connected to the second pipeline through the lower stainless steel flange. Preferably,

[0032] The upper stainless steel flange and the lower stainless steel flange are respectively connected to a water cooler through water cooling pipes.

[0033] In a preferred embodiment of the present utility model:

[0034] A sealing ring is provided between the upper stainless steel flange and the upper end opening of the furnace tube, and / or a sealing ring is provided between the lower stainless steel flange and the lower end opening of the furnace tube.

[0035] The present utility model can specifically adopt the following solutions:

[0036] Furnace body: The furnace body is the core of the gallium oxide thick film growth system, and its design is crucial for the growth of high-quality gallium oxide epitaxial layers. The furnace body of the present utility model adopts a double-temperature zone design with adjustable upper and lower temperatures. Each temperature zone consists of 8-12 silicon molybdenum rod heating elements, and is equipped with a platinum-rhodium thermocouple and / or an infrared thermometer for accurately monitoring and controlling the temperature. The furnace body is made of corundum material with relatively high thermal stability, with an inner diameter of 90 mm, and can accommodate a 2-inch substrate. The upper and lower ends of the furnace tube adopt water-cooled stainless steel flanges and are sealed with double rubber rings to ensure the airtightness of the system at high temperatures.

[0037] High-temperature reaction chamber: The high-temperature reaction chamber is made of alumina crucible with high temperature resistance and high chemical stability, including a crucible body and an end cover. The end cover is used to press the substrate for growth, and a groove for placing the substrate is opened on the end cover, which can ensure the stability and good airtightness of the substrate under high temperature conditions.

[0038] Gas flow control system: During the epitaxial growth process of gallium oxide, the ratio of the gases entering the growth chamber is controlled by a multi-channel mass flowmeter. The main gases used are argon (Ar) and oxygen (O2). By accurately controlling the ratio of these gases, the chemical balance and gas phase environment during the growth process are maintained.

[0039] Pressure dynamic control system: The air pressure in the growth chamber is adjusted through a mechanical pump and a vacuum flowmeter. By controlling the gas flow rate and the vacuum pumping rate, the dynamic balance of the pressure in the chamber is achieved, ensuring stable growth conditions during the epitaxial growth process.

[0040] The method for rapid epitaxy of gallium oxide using the double-temperature zone vertical gallium oxide growth furnace includes the following steps:

[0041] (1) Place the growth substrate in the upper temperature zone of the furnace body and place the gallium oxide raw material source in the lower temperature zone; wherein, the substrate is a single crystal sapphire or quartz substrate, and the substrate size is 2 inches; the gallium oxide raw material source is a mixture of high-purity gallium oxide powder and nano-graphite powder with a molar ratio of 1:20;

[0042] (2) Heat the upper temperature zone to the epitaxial growth temperature and heat the lower temperature zone to the temperature at which the gallium oxide raw material source generates gas phase;

[0043] (3) Through the gas flow control system, control the gas ratio entering the growth chamber; wherein, the gas is argon (Ar) and oxygen (O2), and the gas flow ratio is precisely controlled by a multi-channel flowmeter;

[0044] (4) Utilize the pressure dynamic control system, including a mechanical pump, a vacuum valve, and a vacuum flowmeter, to maintain the pressure dynamic balance in the growth chamber by adjusting the pumping speed of the vacuum pump and controlling the gas flow entering the growth chamber;

[0045] (5) Adjust the temperature difference between the two temperature zones to control the growth rate and crystal quality of the epitaxial layer; wherein, during the heating process, control the temperature of the upper temperature zone to be higher than that of the lower temperature zone to prevent excessive gallium oxide crystal nuclei from appearing on the substrate; during the cooling process, adopt the cooling mode in which the temperature of the upper temperature zone is higher than that of the lower temperature zone to prevent secondary crystallization on the surface of the β-Ga2O3 thin film.

[0046] The utility model places the growth substrate in the upper temperature zone of the furnace body and places the gallium oxide raw material source in the lower temperature zone; heats the upper temperature zone to the epitaxial growth temperature, and at the same time heats the lower temperature zone to the temperature at which the gallium oxide raw material source can generate gas phase. The temperature zones are designed as a two-temperature zone with adjustable upper and lower temperatures to ensure that the temperature of the source is higher than that of the substrate to maintain a sufficient Ga2O3 vapor incident collision flux. The utility model can precisely control the ratio of argon (Ar) and oxygen (O2) entering the growth chamber through the gas flow control system to ensure a stable gas phase environment. The utility model utilizes the pressure dynamic control system to maintain the pressure dynamic balance in the growth chamber by controlling the gas flow and the vacuum pumping rate of the vacuum pump. The utility model realizes the precise control of the growth rate of the epitaxial layer and optimizes the crystal quality of the epitaxial layer by adjusting the temperature difference between the two temperature zones and the gas flow.

[0047] The structure of this new device is ingenious, combining multiple systems, with a compact structure, saving space, simple operation, and a convenient growth method. It is inexpensive and can well realize the rapid epitaxy of gallium oxide, contributing to the research on the growth of gallium oxide thin films, especially suitable for application scenarios that require high-quality crystal structures and rapid growth rates. Description of the Drawings

[0048] Figure 1Schematic structural diagram of the double-temperature-zone vertical gallium oxide growth furnace of the present utility model;

[0049] Among them, 1.1 - furnace tube, 1.2 - upper temperature zone, 1.3 - lower temperature zone, 1.4 - temperature detection device, 1.5 - upper stainless steel flange, 1.6 - lower stainless steel flange, 1.7 - first control valve, 1.8 - first pipeline, 1.9 - water-cooled tube, 1.10 - water chiller, 1.11 - heat insulation layer, 1.12 - heat insulation furnace plug, 2.1 - multi-channel flowmeter, 2.4 - first gas, 2.5 - second gas, 3.1 - vacuum flowmeter, 3.2 - second pipeline, 3.3 - second control valve, 3.4 - vacuum pump, 4.1 - high-temperature reaction chamber, 4.2 - gallium oxide and graphene powder, 4.3 - end cover;

[0050] Figure 2 Crystal quality analysis results of the gallium oxide epitaxial layer prepared in Examples 1-3;

[0051] Figure 3 Microscope image of the surface morphology of the gallium oxide epitaxial layer prepared in Example 1;

[0052] Figure 4 Microscope image of the surface morphology of the gallium oxide epitaxial layer prepared in Example 1. Specific embodiments

[0053] The following further describes the specific embodiments of the present utility model in conjunction with the accompanying drawings. It should be noted here that the description of these embodiments is used to help understand the present utility model, but does not constitute a limitation to the present utility model. In addition, the technical features involved in the various embodiments of the present utility model described below can be combined with each other as long as they do not conflict with each other.

[0054] Example 1

[0055] As Figure 1 shown, a double-temperature-zone vertical gallium oxide growth furnace includes a furnace body, a gas flow control system, and a pressure dynamic control system;

[0056] The furnace body includes a furnace tube 1.1, an upper temperature zone 1.2 arranged at the upper part of the furnace tube 1.1, a lower temperature zone 1.3 arranged at the lower part of the furnace tube 1.1, and a high-temperature reaction chamber 4.1 arranged in the middle of the furnace tube 1.1. The high-temperature reaction chamber 4.1 is an alumina crucible, including a crucible body and an end cover 4.3. The crucible body is used to place evenly mixed gallium oxide and graphene powder 4.2. The end cover 4.3 is provided with a groove for placing a substrate, on which a thin film is grown through a high-temperature redox reaction. The upper temperature zone 1.2 includes eight heatable silicon-molybdenum rods arranged circumferentially at the upper part of the furnace tube 1.1; the lower temperature zone 1.3 includes eight heatable silicon-molybdenum rods arranged circumferentially at the lower part of the furnace tube 1.1; a thermal insulation layer 1.11 made of aluminum silicate fiber is provided on the outer periphery of the furnace tube 1.1; thermal insulation plugs 1.12 are respectively provided at the openings at the upper and lower ends of the furnace tube 1.1; a temperature detection device 1.4 is provided in the middle of the furnace tube 1.1, and the temperature detection device 1.4 uses a platinum-rhodium thermocouple;

[0057] The gas flow control system includes a multi-channel flowmeter 2.1 and a first gas 2.4 and a second gas 2.5 respectively connected to the multi-channel flowmeter 2.1. The multi-channel flowmeter 2.1 is connected to the upper end opening of the furnace tube 1.1 via a first pipe 1.8. A first control valve 1.7 is installed on the first pipe 1.8. The first control valve 1.7 is a vacuum valve. The first gas 2.4 is argon (Ar) and the second gas 2.5 is oxygen (O2). The multi-channel flowmeter 2.1 is controlled by vacuum valves with the argon (Ar) and oxygen (O2). The upper end opening of the furnace tube 1.1 is connected to the first pipe 1.8 via an upper stainless steel flange 1.5. A double-layer sealing ring is provided between the upper stainless steel flange 1.5 and the upper end opening of the furnace tube 1.1. The upper stainless steel flange 1.5 is connected to a water chiller 1.10 via a water cooling pipe 1.9 for cooling.

[0058] The pressure dynamic control system includes a vacuum flowmeter 3.1 for detecting pressure changes in the furnace tube 1.1 and a vacuum pump 3.4 connected to the furnace tube 1.1 via a second pipeline 3.2. The vacuum pump 3.4 can be a mechanical pump to evacuate the furnace tube 1.1 to control the pressure stability. The vacuum flowmeter 3.1 is connected to the lower end opening of the furnace tube 1.1. A second control valve 3.3 is installed on the second pipeline 3.2. The second control valve 3.3 is a vacuum valve to prevent unsatisfactory vacuuming effect or gas from entering the interior of the furnace tube 1.1. The lower end opening of the furnace tube 1.1 is connected to the second pipeline 3.2 via a lower end stainless steel flange 1.6. A double-layer sealing ring is provided between the lower end stainless steel flange 1.6 and the lower end opening of the furnace tube 1.1. The lower end stainless steel flange 1.6 is connected to a water cooler 1.10 via a water cooling pipe 1.9 for cooling. The water cooler 1.10 must be turned on before heating.

[0059] During use, gallium oxide and graphene powder 4.2 are mixed evenly in a molar ratio of 1:20 and then placed in an alumina crucible. The cleaned and dried substrate is placed in the groove of the end cap 4.3. Open the top flange 1.5, and place the alumina crucible through the bracket at the position between the upper temperature zone 1.2 and the lower temperature zone 1.3. Ensure that the substrate is in the upper temperature zone 1.2, and the gallium oxide and graphene powder 4.2 are in the lower temperature zone 1.3. Then install the heat insulation furnace plug 1.12, cover the flange cover of the upper stainless steel flange 1.5, and tighten the first control valve 1.7. After adjusting the temperatures of each temperature zone, turn on the water cooler 1.10, and the condensed water cools the upper stainless steel flange 1.5 and the lower stainless steel flange 1.6 along the water cooling pipe 1.9. Set the upper temperature zone 1.2 to 950 °C, the lower temperature zone 1.3 to 1450 °C, the rate to 5 °C / min, and the upper temperature zone 1.2 to be preheated for 30 min. As the heating program starts, the temperature detection device 1.4 monitors the temperature change. Turn on the vacuum pump 3.4 and fully open the second control valve 3.3, and use the vacuum flowmeter 3.1 to monitor the pressure in the furnace tube 1.1 to be pumped below 10 Pa. Close the second control valve 3.3, introduce the first gas 2.4 argon (Ar), open the vacuum valve between the first control valve 1.7 and the argon (Ar) and the multi-channel flowmeter 2.1, and the argon (Ar) enters the inside of the furnace tube 1.1 through the first pipeline 1.8. The multi-channel flowmeter 2.1 controls the flow rate of argon (Ar) to be 500 sccm, and observe through the vacuum flowmeter 3.1 that the pressure stabilizes at 3×10 3 Pa and maintain for 5 min. Then close the first control valve 1.7 and the vacuum valve between the argon (Ar) and the multi-channel flowmeter 2.1, open the second control valve 3.3, and pump the pressure in the furnace tube 1.1 below 10 Pa again, and then repeat the operation of introducing the above argon (Ar). Evacuating and introducing argon (Ar) are to remove the impurity gases adsorbed on the tube wall, tube plug and crucible and fill the furnace tube 1.1 with stable argon (Ar). This is one cycle, and repeat three times until the last time of introducing argon (Ar), and the vacuum flowmeter 3.1 monitors that the pressure stabilizes at 3×10 3 Pa. Until the lower temperature zone 1.3 rises to 1450 °C, introduce the second gas 2.5 oxygen (O2), open the first control valve 1.7 and the vacuum valve between the oxygen (O2) and the multi-channel flowmeter 2.1, control the flow rate of oxygen (O2) through the multi-channel flowmeter 2.1 to be the flow rate required for epitaxial growth, and by adjusting the second control valve 3.3, stabilize the pressure at 3×10 3pa. As the temperature rises, the gallium oxide and graphene powder 4.2 have started to decompose, and due to the pressure difference caused by the temperature, it rises below the substrate of the end cap 4.3 for film growth. After 2 hours, the lower temperature zone 1.3 cools down, the oxygen (O2) supply is stopped, the vacuum valve between the oxygen (O2) and the multi-channel flowmeter 2.1 is closed, and the oxygen (O2) knob of the multi-channel flowmeter 2.1 is adjusted to 0, ending the epitaxial growth. Once again, control the second control valve 3.3 to stabilize the gas pressure in the furnace tube 1.1 at 3×10 3 pa. Through program setting, the lower temperature zone 1.3 cools down to 800 °C first, and the upper temperature zone 1.2 cools down to 800 °C later, ending the epitaxial growth.

[0060] The β-Ga2O3 thick film is grown by carbothermal reduction method using the above double-temperature zone vertical gallium oxide growth furnace:

[0061] 1. Preparation: Put high-purity Ga2O3 powder and nano-graphite powder into a mixer according to a molar ratio of 1:20. After fully mixing evenly, pour it into an alumina crucible. The sapphire substrate is ultrasonically cleaned successively with acetone, ethanol, and deionized water. After each cleaning for 5 minutes, it is dried with nitrogen and placed in the groove of the end cap of the alumina crucible for standby.

[0062] 2. Loading and setting: Put the crucible with the sapphire substrate into the growth furnace, ensuring that the mixed powder of Ga2O3 powder and graphite powder is in the lower temperature zone 1.3, while the sapphire substrate is in the upper temperature zone 1.2. The temperatures of the upper and lower temperature zones are set at 950 °C and 1450 °C respectively.

[0063] 3. Cleaning and gas replacement: Turn on the vacuum system, pump the background vacuum to 10 Pa and then introduce argon (Ar) for cleaning. Repeat the operation 3 times to remove the impurity gases adsorbed on the tube wall, tube plug, and crucible. Subsequently, introduce 500 sccm of argon (Ar) to maintain the pressure in the growth chamber at 3×10 3 Pa, and start the heating program.

[0064] 4. Heating and growth process: During the heating process, to prevent excessive Ga2O3 crystal nuclei from appearing on the sapphire substrate, a heating mode with the upper temperature zone 1.2 higher than the lower temperature zone 1.3 is adopted. During the growth process, keep the temperature of the upper temperature zone 1.2 lower than that of the lower temperature zone 1.3, and start to introduce oxygen (O2) with a flow rate of 100 sccm, and the growth time is set to 2 hours.

[0065] 5. Cooling process: After the growth is completed, turn off the oxygen (O2) supply and perform the cooling operation. To prevent secondary crystallization on the surface of the β-Ga2O3 film during the cooling process, the same cooling mode with the upper temperature zone 1.2 higher than the lower temperature zone 1.3 is also adopted.

[0066] Sample extraction and characterization: After cooling to room temperature, the sample was taken out for subsequent characterization and analysis.

[0067] Example 2

[0068] The structure of the two-zone vertical gallium oxide growth furnace and the method for growing β-Ga2O3 thick film by carbothermal reduction method in Example 2 are the same as those in the example, except that the flow rate of oxygen (O2) is 20 sccm.

[0069] Example 3

[0070] The structure of the two-zone vertical gallium oxide growth furnace and the method for growing β-Ga2O3 thick film by carbothermal reduction method in Example 3 are the same as those in the example, except that the flow rate of oxygen (O2) is 10 sccm.

[0071] The embodiments of the present utility model have been described in detail above in conjunction with the accompanying drawings, but the present utility model is not limited to the described embodiments. For those skilled in the art, without departing from the principle and spirit of the present utility model, various changes, modifications, substitutions, and variations made to these embodiments still fall within the protection scope of the present utility model.

Claims

1. A vertical gallium oxide growth furnace with two temperature zones, characterized in that The growth furnace includes a furnace body, a gas flow control system, and a pressure dynamic control system; The furnace body includes a furnace tube, an upper temperature zone provided at the upper part of the furnace tube, a lower temperature zone provided at the lower part of the furnace tube, and a high-temperature reaction chamber provided in the middle of the furnace tube; The gas flow control system includes a multi-channel flowmeter, a first gas and a second gas respectively connected to the multi-channel flowmeter. The multi-channel flowmeter is connected to the upper end opening of the furnace tube through a first pipeline, and a first control valve is installed on the first pipeline; The pressure dynamic control system includes a vacuum flowmeter and a vacuum pump connected to the furnace tube through a second pipeline. The vacuum flowmeter is connected to the lower end opening of the furnace tube, and a second control valve is installed on the second pipeline.

2. The growth furnace according to claim 1, wherein: The upper temperature zone includes heatable silicon molybdenum rods arranged circumferentially at the upper part of the furnace tube.

3. The growth furnace according to claim 2, wherein: The number of the heatable silicon molybdenum rods is 8 - 12.

4. The growth furnace according to claim 1, wherein: The lower temperature zone includes heatable silicon molybdenum rods arranged circumferentially at the lower part of the furnace tube.

5. The growth furnace according to claim 4, wherein: The number of the heatable silicon molybdenum rods is 8 - 12.

6. The growth furnace according to claim 1, wherein: A heat insulation layer is provided on the outer periphery of the furnace tube.

7. The growth furnace according to claim 6, wherein: The heat insulation layer is aluminosilicate fiber and / or silicon fiber.

8. The growth furnace according to claim 1, wherein: Heat insulation furnace plugs are respectively provided at the openings at the upper and lower ends of the furnace tube.

9. The growth furnace according to claim 1, wherein: A temperature detection device is provided in the middle of the furnace tube.

10. The growth furnace according to claim 9, wherein: The temperature detection device is a platinum-rhodium thermocouple and / or an infrared thermometer.

11. The growth furnace according to claim 1, wherein: The first control valve is a vacuum valve; and / or, The first gas is argon; and / or, The second gas is oxygen; and / or, Vacuum valves are respectively installed on the pipelines connecting the first gas and the second gas to the multi-channel flowmeter; and / or, The second control valve is a vacuum valve.

12. The growth furnace according to claim 1, wherein: The high-temperature reaction chamber is an alumina crucible; and / or, The high-temperature reaction chamber includes a crucible body and an end cover.

13. The growth furnace according to claim 12, wherein: A groove for placing a substrate is provided on the end cover.

14. The growth furnace according to claim 1, wherein: The upper end opening of the furnace tube is connected to the first pipeline through an upper stainless steel flange, and the lower end opening of the furnace tube is connected to the second pipeline through a lower stainless steel flange.

15. The growth furnace according to claim 14, wherein: The upper stainless steel flange and the lower stainless steel flange are respectively connected to a water cooler through a water cooling pipe.

16. The growth furnace according to claim 14, wherein: A sealing ring is provided between the upper stainless steel flange and the upper opening of the furnace tube, and / or a sealing ring is provided between the lower stainless steel flange and the lower opening of the furnace tube.

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