Large-size diamond growth MPCVD device capable of preventing airflow impact and working method of large-size diamond growth MPCVD device

Abstract

The invention relates to a large-size diamond growth MPCVD device capable of preventing airflow impact and a working method of the large-size diamond growth MPCVD device, and belongs to the related field of diamond preparation. The device comprises a reaction cavity, an outer ring cooling cavity, an inner ring gas uniformizing cavity, a process gas buffer cavity and a process gas inlet system, the outer ring cooling cavity is arranged at the top of an outer ring of a cavity body of the reaction cavity, the upper portion of the outer ring cooling cavity is connected with the process gas buffer cavity, and the inner ring gas uniformizing cavity is arranged at the top of the center of the cavity body of the reaction cavity. The reaction cavity is isolated from the process gas buffer cavity by the inner ring gas uniformizing cavity; and process gas inlet systems are symmetrically arranged on two sides of the upper sealing cover of the cavity at the top of the process gas buffer cavity. The invention further provides a working method of the large-size diamond growth MPCVD device capable of preventing airflow impact. The device is reasonable in structural design, safe and reliable, when the downward microwave entering mode is adopted, after airflow enters from the upper portion of the cavity, the airflow is prevented from impacting a diamond substrate, the uniformity of diamond is improved, and the use requirement is met.

Description

Technical Field

[0001] The invention relates to a device and a working method thereof, in particular to a large-size diamond growth MPCVD device and a working method thereof that are resistant to airflow impact, and belongs to the field related to diamond preparation. Background Art

[0002] Large-size diamond growth MPCVD device: microwave plasma chemical vapor deposition equipment, also known as MPCVD (Microwave Plasma Chemical Vapor Deposition), is a device used to grow large-size single crystal and polycrystalline diamonds. The size of the grown diamonds can reach 4-6 inches.

[0003] Airflow impact: refers to the microwave plasma chemical vapor deposition equipment used to grow large-sized diamonds. Due to the large air intake volume and fast air intake rate, a large impact force will be generated when the gas just enters, forming an airflow impact.

[0004] Plasma: It is an ionized gaseous substance composed of positive and negative ions produced when atoms and atomic groups are deprived of some of their electrons and ionized.

[0005] The main methods for synthesizing artificial diamonds include high temperature and high pressure (HTHP), microwave plasma chemical vapor deposition (MPCVD), direct current arc plasma jet (DCAPJ) / hot wire chemical vapor deposition (HFCVD), etc. MPCVD has the advantages of high plasma energy density, low impurity content, and good controllability. It is one of the most promising methods for synthesizing high-quality diamonds. The working principle of MPCVD equipment is to transmit the microwaves generated by the microwave generator into the reaction chamber of the reaction equipment through a waveguide transmission system, and introduce a mixed gas of methane and hydrogen into the reaction chamber. Under the excitation of microwaves, glow discharge is generated in the reaction chamber, so that the molecules of the reaction gas are ionized to generate plasma, and a diamond film is deposited on the diamond substrate.

[0006] Currently, in the field of large-scale diamond growth MPCVD devices that are resistant to gas flow impact, there is no solution similar to the present invention in the type of downward microwave equipment.

[0007] In the prior art, large-scale diamond growth MPCVD devices that prevent gas flow impact are devices that introduce mixed gases such as methane and hydrogen into the reaction chamber of the MPCVD device during operation. In order to allow the gas to be more evenly distributed in the chamber after entering, the gas inlet is generally distributed at the center of the chamber cover directly above the chamber, or a number of air inlet holes are evenly distributed on the chamber cover. In large-scale MPCVD equipment, due to the large gas flow rate, the gas suddenly enters the vacuum chamber with a large impact force, which can cause the diamond substrate above the workbench to be blown away from its original position or even blown off the workbench, thereby affecting the growth of diamond crystals. Summary of the invention

[0008] The purpose of the present invention is to overcome the above-mentioned deficiencies in the prior art and to provide a large-size diamond growth MPCVD device and its working method which has a reasonable structural design, is safe and reliable, and adopts a downward microwave form. After the airflow enters the cavity from the top, it avoids the airflow impacting the diamond substrate, thereby improving the uniformity of the diamond.

[0009] The technical solution adopted by the present invention to solve the above-mentioned problem is: the large-size diamond growth MPCVD device that is resistant to airflow impact includes a process gas inlet system, a coolant circulation pipeline and a temperature measurement system, and is characterized in that: it also includes a reaction chamber, an outer ring cooling chamber, an inner ring uniform gas chamber and a process gas buffer chamber, the outer ring cooling chamber is arranged at the top of the cavity outer ring of the reaction chamber, the upper part of the outer ring cooling chamber is connected to the process gas buffer chamber, the inner ring uniform gas chamber is arranged at the top of the cavity center of the reaction chamber, and the inner ring uniform gas chamber isolates the reaction chamber from the process gas buffer chamber; the reaction chamber includes a workbench, a quartz ring, a diamond substrate and plasma, the workbench is located in the center of the reaction chamber, the diamond substrate is placed above the workbench, and the plasma is formed in a spherical shape on the diamond substrate; under the action of the microwave field, microwaves are fed into the reaction chamber from the bottom, pass through the quartz ring and enter the reaction chamber, the process gas enters from the inner ring uniform gas chamber above the reaction chamber, and is placed above the diamond substrate The inner ring uniform gas cavity comprises an inner ring chassis, an inner ring outer wall, an inner microwave shielding ring, an inner ring upper cover, a uniform gas pipe, a temperature measuring channel and a coolant inlet and outlet. An inner microwave shielding ring is arranged on the outer side of the inner ring outer wall, and is in elastic and close contact with the outer ring cooling cavity. The inner ring chassis matches with the inner ring upper cover to form a cavity for heat transfer of the coolant. A temperature measuring channel is arranged at the center of the inner ring uniform gas cavity, and a plurality of uniform gas pipes evenly distributed are arranged on the inner ring uniform gas cavity. The process gas buffer cavity comprises a cavity upper sealing cover and a temperature measuring pipeline. The top of the process gas buffer cavity is the cavity upper sealing cover, and the process gas inlet system is symmetrically arranged on both sides of the cavity upper sealing cover. The coolant circulation pipeline is divided into a coolant inlet pipeline and a coolant outflow pipeline. The temperature measuring system comprises an infrared thermometer and an infrared thermometer bracket. The infrared thermometer is arranged on the infrared thermometer bracket. The infrared thermometer passes through the quartz glass above the temperature measuring pipeline and directly monitors the plasma through the temperature measuring pipeline.

[0010] Preferably, the outer ring cooling cavity of the present invention comprises a cavity lower end cover, a cavity outer wall, a cavity inner wall, a cooling liquid inlet duct, a cavity upper end cover and an outer microwave shielding ring. The outer microwave shielding ring is installed on the cavity outer wall. The cooling liquid enters the cavity directly from the cooling liquid inlet duct in the cavity to the bottom of the cavity until the sealed cavity is filled with cooling liquid, and then the cooling liquid flows out from the outlet above the cavity upper end cover.

[0011] Preferably, an annular groove is provided on the inner ring chassis of the present invention and is welded integrally with the inner ring upper cover.

[0012] Preferably, the process gas buffer chamber of the present invention also includes a lower support plate and an upper support plate, and the coolant inlet pipeline and the coolant outlet pipeline are both two metal hollow pipes, one is fixed on the lower support plate, passes through the sealing cover on the cavity, and enters the outer ring uniform air cavity, and the other is fixed on the upper support plate, passes through the sealing cover on the cavity, and enters the inner ring uniform air cavity.

[0013] The present invention also provides a working method of a large-size diamond growth MPCVD device that is resistant to airflow impact, which is characterized by the following specific steps: (S1) under the action of a microwave field, microwaves are fed from the bottom of the reaction chamber, pass through a quartz ring and enter the reaction chamber, process gas enters from an inner ring uniform gas chamber above the reaction chamber, and is excited to a plasma state above the diamond substrate. The plasma is formed in a spherical shape on the diamond substrate, and the substrate is heated to a certain temperature by using the high temperature of the plasma; (S2) an outer ring cooling chamber isolates the high-speed process gas from the reaction chamber, coolant is introduced into the interior, and at the same time plays an auxiliary role in controlling the working temperature in the reaction chamber; the coolant enters the cooling liquid conduit in the cavity and directly enters the bottom of the cavity until the sealed cavity is filled with coolant, and the coolant flows out from the outlet above the upper end cover of the cavity; (S3) The inner ring uniform gas chamber isolates the reaction chamber from the process gas buffer chamber. An annular groove is set on the inner ring bottom plate and welded to the inner ring cover to form a cavity for heat transfer of the coolant; a number of evenly distributed uniform gas pipes are set on the inner ring uniform gas chamber. After the process gas is buffered in the process gas buffer chamber, the speed of the process gas has dropped, and then it flows out through the uniform gas pipe and enters the reaction chamber; (S4) The process gas enters the process gas buffer chamber through the metal pipe and interface. After filling the process gas buffer chamber, the speed of the air flow slows down and becomes stable in the buffer chamber; (S5) The process gas passes through the main air inlet pipeline, passes through the tee, and the metal channel is divided into two, enters the metal interface from the elbows on both sides, and passes through the center hole of the flange connected to the metal interface; the gas inlet diameter is set to gradually increase for air flow buffering.

[0014] Compared with the prior art, the present invention has the following advantages and effects: the overall structural design is reasonable, safe and reliable; when the downward microwave form is adopted, the airflow enters from the top of the cavity, which can prevent the airflow from impacting the diamond substrate; this device avoids the airflow impacting the diamond substrate and can improve the uniformity of the diamond. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of the overall cross-sectional structure of an embodiment of the present invention.

[0016] Figure 2 Schematic diagram of the structure of the reaction chamber in the embodiment of the present invention.

[0017] Figure 3 It is a schematic diagram of the three-dimensional structure of the outer ring cooling cavity in an embodiment of the present invention.

[0018] Figure 4 It is a schematic diagram of the cross-sectional structure of the outer ring cooling cavity in an embodiment of the present invention.

[0019] Figure 5 It is a schematic diagram of the three-dimensional structure of the inner ring uniform air cavity in an embodiment of the present invention.

[0020] Figure 6 It is a schematic diagram of the cross-sectional structure of the inner ring uniform air cavity in an embodiment of the present invention.

[0021] Figure 7 Schematic diagram of the cross-sectional structure of the process gas buffer chamber in an embodiment of the present invention.

[0022] In the figure: reaction chamber 1, outer ring cooling chamber 2, inner ring uniform gas chamber 3, process gas buffer chamber 4, process gas inlet system 5, coolant circulation pipeline 6, temperature measurement system 7; Reaction chamber 1: workbench 11, quartz ring 12, diamond substrate 13, plasma 14; Outer ring cooling cavity 2: cavity lower end cover 21, cavity outer wall 22, cavity inner wall 23, cooling liquid inlet conduit 24, cavity upper end cover 25, outer microwave shielding ring 26; Inner ring gas-uniform cavity 3: inner ring bottom plate 31, inner ring outer wall 32, inner microwave shielding ring 33, inner ring upper cover 34, gas-uniform tube 35, temperature measuring channel 36, cooling liquid inlet and outlet 37; Process gas buffer chamber 4: upper sealing cover 41 of the chamber, lower support plate 42, upper support plate 43, coolant inlet pipeline 44, temperature measuring pipeline 45, coolant outlet pipeline 46; Temperature measuring system 7: infrared thermometer bracket 70, infrared thermometer 71. DETAILED DESCRIPTION

[0023] The present invention will be further described in detail below with reference to the accompanying drawings and by way of examples. The following examples are intended to explain the present invention but the present invention is not limited to the following examples.

[0024] Example

[0025] See also Figures 1 to 7 The large-size diamond growth MPCVD device for preventing airflow impact in this embodiment includes a reaction chamber 1, an outer ring cooling chamber 2, an inner ring uniform gas chamber 3, a process gas buffer chamber 4, a process gas inlet system 5, a coolant circulation pipeline 6 and a temperature measurement system 7.

[0026] The reaction chamber 1 of this embodiment includes a reaction chamber 1, a workbench 11, a quartz ring 12, a diamond substrate 13 and a plasma 14. The center of the reaction chamber 1 is the workbench 11 for diamond growth, and the diamond substrate 13 is placed above the workbench 11. Under the action of the microwave field, microwaves are fed from the bottom of the reaction chamber 1, enter the reaction chamber 1 through the quartz ring 12, and the process gas enters from the inner ring uniform gas chamber 3 above the reaction chamber 1, and is excited to a plasma state above the diamond substrate 13. The plasma 14 is formed on the diamond substrate 13 in a spherical shape, and the substrate can be heated to a certain temperature by using the high temperature of the plasma 14.

[0027] The outer ring cooling chamber 2 of this embodiment is at the top of the outer ring of the reaction chamber 1 and is suspended at a certain height above the reaction chamber 1. The process gas buffer chamber 4 is connected above it. The outer ring cooling chamber 2 mainly serves to isolate the high-speed process gas from the reaction chamber 1, and coolant is passed into the inner part, and at the same time, it serves to assist in controlling the working temperature in the reaction chamber 1.

[0028] In this embodiment, the outer ring cooling cavity 2 includes a cavity lower end cover 21, a cavity outer wall 22, a cavity inner wall 23, a coolant inlet duct 24, a cavity upper end cover 25 and an outer microwave shielding ring 26. The outer microwave shielding ring 26 is installed on the cavity outer wall 22 to maintain elastic contact with the equipment cavity wall, which can be one circle or more to prevent microwave leakage; the various components are firmly combined by thermoforming technology to form a sealed cavity, and the coolant is directly passed into the bottom of the cavity from the coolant inlet duct 24 in the cavity until the sealed cavity is filled with coolant, and the coolant flows out from the outlet above the cavity upper end cover 25.

[0029] In this embodiment, the inner ring uniform gas chamber 3 includes an inner ring chassis 31, an inner ring outer wall 32, an inner microwave shielding ring 33, an inner ring upper cover 34, a uniform gas pipe 35, a temperature measuring channel 36 and a coolant inlet and outlet 37. The inner ring uniform gas chamber 3 is at the top of the center of the reaction chamber 1 and is suspended at a certain height directly above the reaction chamber 1. The inner ring uniform gas chamber 3 isolates the reaction chamber 1 from the process gas buffer chamber 4. Between the two chambers, an inner microwave shielding ring 33 is arranged on the outer side of the inner ring outer wall 32, and is in elastic and close contact with the outer ring cooling chamber 2, which can be one circle or more, to prevent microwave leakage. An annular groove is arranged on the inner ring chassis 31, which is welded to the inner ring upper cover 34 to form a cavity for heat transfer of the coolant. A temperature measuring channel 36 is arranged in the center of the inner ring uniform gas chamber 3, and an infrared thermometer 71 reads the temperature of the plasma group through the temperature measuring channel 36. Most importantly, a number of uniformly distributed uniform gas pipes 35 are arranged on the inner ring uniform gas chamber 3. After the process gas is buffered in the process gas buffer chamber 4, the speed has been reduced, and then it flows out through the uniform gas pipes 35 and enters the reaction chamber 1. The gas outlet is arranged just above the diamond substrate 13, and the dispersed gas will not be blown directly onto the diamond substrate 13, but will be evenly dispersed in the reaction chamber 1.

[0030] In this embodiment, the process gas buffer chamber 4 includes a cavity upper sealing cover 41, a lower support plate 42, an upper support plate 43, a coolant inlet pipeline 44, a temperature measuring pipeline 45 and a coolant outflow pipeline 46. The top of the process gas buffer chamber 4 is the cavity upper sealing cover 41, and the process gas inlet system 5 is symmetrically arranged on both sides of the cavity upper sealing cover. The process gas enters the process gas buffer chamber 4 through the metal pipe and the interface. After filling the process gas buffer chamber 4, the speed of the airflow slows down and becomes stable in the buffer chamber.

[0031] This embodiment includes a process gas inlet system 5; the process gas passes through the main inlet pipeline, passes through the tee, and the metal channel is divided into two, and enters the metal interface from the elbows on both sides, and passes through the center hole of the flange connected to the metal interface. The flange and the sealing cover on the cavity are fastened with screws, and an O-ring seal and a microwave shielding ring are set to ensure gas sealing performance and microwave shielding function. The gas inlet diameter is set to gradually increase for airflow buffering.

[0032] In the MPCVD device of this embodiment, in order to avoid the temperature of each cavity being too high, the cavity wall is generally set to a hollow mode, and a coolant is passed inside to cool the cavity. The coolant circulation pipeline 6 is divided into a coolant inlet pipeline 44 and a coolant outlet pipeline 46. The coolant inlet pipeline 44 is two metal hollow pipes, one is fixed on the lower support plate 42, passes through the upper sealing cover 41 of the cavity, and enters the outer ring uniform gas cavity 2; the other is fixed on the upper support plate 43, passes through the upper sealing cover 41 of the cavity, and enters the inner ring uniform gas cavity 3; the coolant outlet pipeline 46 is also two metal hollow pipes, one is fixed on the lower support plate 42, passes through the upper sealing cover 41 of the cavity, and is connected to the outer ring uniform gas cavity 2; the other is fixed on the upper support plate 43, passes through the upper sealing cover 41 of the cavity, and is connected to the inner ring uniform gas cavity 3.

[0033] In this embodiment, the temperature measuring system 7 includes an infrared thermometer bracket 70 and an infrared thermometer 71; the temperature at the plasma group position is monitored in real time by the infrared thermometer 71. The infrared thermometer 71 is arranged at the top of the device, and the plasma group is directly monitored through the quartz glass above the temperature measuring pipe 45 and through the temperature measuring pipe 45.

[0034] The large-scale diamond growth MPCVD device resistant to airflow impact in this embodiment solves the problems of large air intake impact force and uneven air intake in existing large-scale MPCVD equipment.

[0035] Through the above description, those skilled in the art can already implement it.

[0036] In addition, it should be noted that the shapes and names of the parts and components of the specific embodiments described in this specification may be different, and the above content described in this specification is only an example of the structure of the present invention. All equivalent changes or simple changes made based on the structure, features and principles described in the patent concept of the present invention are included in the protection scope of the patent of the present invention. Technicians in the technical field to which the present invention belongs can make various modifications or supplements to the specific embodiments described or replace them in a similar manner, as long as they do not deviate from the structure of the present invention or exceed the scope defined by the claims, they should all fall within the protection scope of the present invention.

Claims

1. A large-size diamond growth MPCVD device that is resistant to gas flow impact, comprising a process gas inlet system (5), a coolant circulation pipeline (6) and a temperature measurement system (7), characterized in that: It also comprises a reaction chamber (1), an outer ring cooling chamber (2), an inner ring uniform gas chamber (3) and a process gas buffer chamber (4), wherein the outer ring cooling chamber (2) is arranged at the top of the outer ring of the reaction chamber (1), the upper part of the outer ring cooling chamber (2) is connected to the process gas buffer chamber (4), the inner ring uniform gas chamber (3) is arranged at the top of the center of the reaction chamber (1), and the inner ring uniform gas chamber (3) isolates the reaction chamber (1) from the process gas buffer chamber (4); the reaction chamber (1) comprises a workbench (11), a quartz ring (12), a diamond substrate (13) and a plasma (14), the workbench (11) is located at the center of the reaction chamber (1), the diamond substrate (13) is placed above the workbench (11), and the plasma (14) is formed in a spherical shape on the diamond substrate (13); microwaves are fed from the bottom of the reaction chamber (1) and enter the reaction chamber (1) through the quartz ring (12); the process gas enters from the inner ring uniform gas chamber (3) above the reaction chamber (1) and is excited to a plasma (14) state above the diamond substrate (13); the inner ring uniform gas chamber (3) includes an inner ring bottom plate (31), an inner ring outer wall (32), an inner microwave shielding ring (33), and an inner ring upper cover ( 34), a uniform gas pipe (35), a temperature measurement channel (36) and a coolant inlet and outlet (37); an inner microwave shielding ring (33) is arranged on the outer side of the inner ring outer wall (32) to be in elastic and close contact with the outer ring cooling cavity (2); the inner ring bottom plate (31) matches the inner ring upper cover (34) to form a cavity for heat transfer of the coolant; a temperature measurement channel (36) is arranged at the center of the inner ring uniform gas cavity (3); a plurality of uniform gas pipes (35) are arranged on the inner ring uniform gas cavity (3); the process gas buffer cavity (4) comprises a cavity upper sealing cover (41) and a temperature measurement pipe (45); the process gas The top of the buffer chamber (4) is a chamber upper sealing cover (41), and process gas inlet systems (5) are symmetrically arranged on both sides of the chamber upper sealing cover (41); the coolant circulation pipeline (6) is divided into a coolant inlet pipeline (44) and a coolant outlet pipeline (46); the temperature measurement system (7) includes an infrared thermometer (71) and an infrared thermometer bracket (70), the infrared thermometer (71) is arranged on the infrared thermometer bracket (70), and the infrared thermometer (71) passes through the quartz glass above the temperature measurement pipeline (45) and directly monitors the plasma (14) through the temperature measurement pipeline (45).

2. The large-size diamond growth MPCVD device with airflow impact resistance according to claim 1 is characterized in that: The outer ring cooling cavity (2) comprises a cavity lower end cover (21), a cavity outer wall (22), a cavity inner wall (23), a coolant inlet conduit (24), a cavity upper end cover (25) and an outer microwave shielding ring (26); the outer microwave shielding ring (26) is installed on the cavity outer wall (22); the coolant flows directly into the cavity bottom from the coolant inlet conduit (24) in the cavity until the sealed cavity is filled with the coolant, and then the coolant flows out from the outlet above the cavity upper end cover (25).

3. The large-size diamond growth MPCVD device with airflow impact resistance according to claim 1, characterized in that: An annular groove is provided on the inner ring bottom plate (31) and is welded integrally with the inner ring upper cover (34).

4. The large-size diamond growth MPCVD device with airflow impact resistance according to claim 1, characterized in that: The process gas buffer chamber (4) further comprises a lower support plate (42) and an upper support plate (43); the coolant inlet pipeline (44) and the coolant outlet pipeline (46) are both two metal hollow pipes, one of which is fixed to the lower support plate (42), passes through the upper sealing cover (41) of the chamber, and enters the outer ring uniform gas chamber (2); and the other is fixed to the upper support plate (43), passes through the upper sealing cover (41) of the chamber, and enters the inner ring uniform gas chamber (3).

5. A method for operating a large-size diamond growth MPCVD device that is resistant to airflow impact, using the large-size diamond growth MPCVD device that is resistant to airflow impact as claimed in any one of claims 1 to 4, characterized in that: The specific steps are as follows: (S1) Under the action of a microwave field, microwaves are fed into the reaction chamber (1) from the bottom, pass through a quartz ring (12) and enter the reaction chamber (1), process gas enters from an inner ring uniform gas chamber (3) above the reaction chamber (1), and is excited to a plasma (14) state above a diamond substrate (13), the plasma (14) is formed in a spherical shape on the diamond substrate (13), and the substrate is heated to a certain temperature by utilizing the high temperature of the plasma (14); (S2) The outer ring cooling chamber (2) is used to isolate the high-speed process gas from the reaction chamber (1), and a cooling liquid is introduced into the inner part, and at the same time, it plays an auxiliary role in controlling the working temperature in the reaction chamber (1); The coolant enters the cavity through the coolant inlet conduit (24) directly into the bottom of the cavity until the sealed cavity is filled with the coolant, and then the coolant flows out from the outlet above the upper end cover (25) of the cavity; (S3) The inner ring uniform gas cavity (3) isolates the reaction cavity (1) from the process gas buffer cavity (4); an annular groove is provided on the inner ring bottom plate (31) and is welded to the inner ring upper cover (34) to form a cavity for heat transfer of the coolant; A plurality of evenly distributed gas-uniform pipes (35) are provided on the inner ring gas-uniform chamber (3); after the process gas is buffered in the process gas buffer chamber (4), the speed of the process gas is reduced, and the process gas then flows out through the gas-uniform pipes (35) and enters the reaction chamber (1); (S4) The process gas passes through the metal pipe and the interface and enters the process gas buffer chamber (4). After the process gas buffer chamber (4) is filled, the speed of the gas flow slows down and becomes stable in the buffer chamber; (S5) The process gas passes through the main inlet pipeline, passes through the tee, and then the metal channel is divided into two. The process gas enters the metal interface from the elbows on both sides and passes through the center hole of the flange connected to the metal interface. The gas inlet diameter is set to gradually increase for airflow buffering.

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