Device and method for regulating and controlling plasma uniformity in MPCVD by using distributed magnetic field

Abstract

The invention discloses a device and method for regulating and controlling plasma uniformity in MPCVD through a distributed magnetic field, the device comprises a reaction cavity, a molybdenum base station, a multi-channel current regulation and control module, an infrared temperature measurement module and a substrate to be grown, the molybdenum base station, the multi-channel current regulation and control module, the infrared temperature measurement module and the substrate to be grown are arranged in the reaction cavity, the substrate to be grown is placed on the molybdenum base station, and a distributed magnetic induction coil group is arranged at the bottom of the molybdenum base station; the multi-channel current regulation and control module is electrically connected with the distributed magnetic induction coil set, and the infrared temperature measurement module is installed on the side wall of the reaction cavity and collects the temperature distribution characteristics of the diamond above the base table in real time. The plasma uniformity can be improved, the plasma temperature difference on the growth substrate is reduced, the discharge uniformity is improved, and the diamond growth uniformity is further improved; meanwhile, the device is high in regulation and control flexibility, supports an open-loop presetting mode and a closed-loop feedback mode, adapts to bases of different sizes, and can quickly adapt to different diamond growth process requirements by adjusting coil current.

Description

Technical Field

[0001] This invention relates to a device and method for controlling plasma homogeneity in MPCVD using a distributed magnetic field, belonging to the field of microwave plasma chemical vapor deposition technology. Background Technology

[0002] Existing MPCVD technology, with its advantages of low temperature, high purity, and fast growth rate, is widely used in the preparation of diamond materials in fields such as semiconductors, tool coatings, and optical windows.

[0003] In existing technologies, plasma uniformity control methods mainly focus on microwave power matching, reactive gas ratio optimization, substrate temperature gradient adjustment, and cavity structure improvement. However, in applications with large-size substrates (such as Φ100mm and above), these control methods have significant limitations: microwave-excited plasma tends to exhibit radial distribution differences with "high density at the center and low density at the edges," resulting in thickness uniformity deviations exceeding 15% and poor quality consistency during diamond growth, severely restricting the industrial application of large-size diamonds. Specifically, microwave power adjustment can simultaneously affect the growth rate, gas ratio control has a limited range, and cavity structure modification suffers from high costs and poor compatibility, failing to fundamentally solve the uniformity problem of plasma spatial confinement. Summary of the Invention

[0004] The purpose of this invention is to address the problems existing in the prior art by providing a device and method for controlling plasma homogeneity in MPCVD using a distributed magnetic field.

[0005] The technical solution provided by this invention to solve the above-mentioned technical problems is: a device for controlling the plasma homogeneity in MPCVD using a distributed magnetic field, comprising a reaction chamber and a molybdenum substrate, a multi-channel current control module, an infrared temperature measurement module, and a substrate to be grown, all disposed within the reaction chamber. The substrate to be grown is placed on the molybdenum substrate, and a distributed magnetic induction coil group is provided at the bottom of the molybdenum substrate. The multi-channel current control module is electrically connected to the distributed magnetic induction coil group, and the infrared temperature measurement module is installed on the side wall of the reaction chamber to collect the diamond temperature distribution characteristics above the substrate in real time.

[0006] A further technical solution is that the distributed magnetic induction coil group includes several groups of concentric coils.

[0007] A further technical solution is that the coils of the several sets of concentric circles are divided into N concentric ring regions along the radial direction of the molybdenum base. Each region independently embeds a set of coils, and the number of coil turns increases with the increase of the region radius. The coil axis is perpendicular to the surface of the base.

[0008] A further technical solution is that the molybdenum base is divided into three concentric annular regions along the radial direction, namely the inner ring, the middle ring, and the outer ring, and the inner ring, the middle ring, and the outer ring are respectively embedded with 5-10 turns, 10-15 turns, and 15-20 turns of coil.

[0009] A further technical solution is that the embedding depth of the distributed magnetic induction coil group is 5-10 mm from the surface of the molybdenum base.

[0010] A further technical solution is that the distributed magnetic induction coil group includes M groups of coils evenly arranged in a matrix or equilateral triangular array along the surface of the molybdenum base.

[0011] A further technical solution is that the number of coil groups M is greater than or equal to four, and the number of turns in a single coil group is 6-10 turns.

[0012] A further technical solution is that the formula for calculating the spacing of the M groups of coils is:

[0013] In the formula: m For spacing; d The diameter is along the molybdenum abutment; M This represents the number of coil groups.

[0014] A method for controlling plasma homogeneity in MPCVD using a distributed magnetic field, the specific steps of which are as follows: Step 1: Equipment Pretreatment; The coil assembly is embedded inside the base according to the preset scheme, connected to the multi-channel current control module, and the infrared temperature measurement module is calibrated; then the molybdenum base is installed into the reaction chamber, sealed, and evacuated to a vacuum degree of 1-5 Pa through the vacuum system, and a mixture of methane and hydrogen reaction gas is introduced. Step 2: Coil initialization; Select the layout scheme according to the base size, and set the initial current of each group of coils to 3-3.5A through the multi-channel current control module; Step 3: Plasma excitation; Start the microwave source at a frequency of 2.45 GHz to excite the reactive gas to form plasma. Gradually increase the microwave power to 6-8 kW and the gas pressure to around 15 kPa to reach the target temperature for diamond growth. Step 4: Dynamic control of the magnetic field; Open-loop mode: The initial current is continuously maintained or the current is adjusted according to the growth stage based on the preset process parameters; Closed-loop mode: The infrared temperature monitoring module collects the temperature distribution at different points in the radial direction of the diamond in real time. If the temperature difference exceeds 50°C, the multi-channel current control module automatically adjusts the coil current in the corresponding area until the temperature difference is less than or equal to 50°C.

[0015] The present invention has the following beneficial effects: the present invention can improve plasma uniformity, reduce plasma temperature differences on the growth substrate, improve discharge uniformity, and thus improve diamond growth uniformity; at the same time, the device has high control flexibility, supports both open-loop preset and closed-loop feedback modes, adapts to different sized substrates, and can quickly adapt to different diamond growth process requirements by adjusting the coil current. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of the device of the present invention; Figure 2 This is a schematic diagram illustrating an example of concentric circle distribution in this invention; Figure 3 This is a diagram showing the silicon wafer temperature before adjustment in this invention; Figure 4 This is a temperature diagram of the silicon wafer after temperature regulation in this invention; Figure 5 This is a flowchart of plasma magnetic field control. Detailed Implementation

[0017] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0019] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can also refer to a mechanical connection. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0020] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0021] For ease of understanding, the following explains some key terms in this embodiment: Reaction chamber 1 is a sealed container used for chemical vapor deposition reactions, and its internal environment is precisely controlled to support the diamond growth process. It is a cylindrical MPCVD reaction chamber: it is both a microwave resonant cavity and a plasma reaction chamber.

[0022] The molybdenum stage 2 is a support structure for placing the substrate 6 to be grown. Its main function is to support the substrate and provide a uniform heating environment. Molybdenum is a high-temperature resistant and conductive material, allowing single-crystal diamond seed crystals or silicon wafers to be placed on the molybdenum stage for growth experiments.

[0023] The distributed magnetic induction coil group 3 consists of multiple groups of coils, using high-temperature resistant copper coils (temperature resistance ≥800℃), which are arranged at the bottom of the molybdenum base 2.

[0024] The multi-channel current regulation module 4 is an electronic device used to control the current of each coil in the distributed magnetic induction coil group 3. This module 4 can precisely adjust the current flowing through each coil according to a preset program or real-time feedback signal, thereby achieving fine-grained control of the magnetic field distribution.

[0025] It corresponds one-to-one with the coil group (N channel or M channel), supports independent current adjustment, has an adjustment range of 0-5A, a response speed of ≤10ms, and can achieve dynamic adjustment by preset current parameters through PLC programming or by receiving feedback signals; The infrared temperature measurement module 5 is a non-contact temperature measurement device installed on the side wall of the reaction chamber 1. This module 5 receives infrared radiation emitted from the diamond surface, collects the temperature distribution characteristics of the diamond above the base in real time, and outputs the data to the current control module to form a closed-loop control.

[0026] The substrate 6 is the base material on which diamond material is deposited and grown, typically a diamond seed crystal or a silicon wafer. This substrate 6 is placed on a molybdenum abutment 2 and directly exposed to the plasma environment.

[0027] like Figure 1 As shown, this embodiment provides a device for controlling plasma homogeneity in MPCVD using a distributed magnetic field, including a reaction chamber 1, which is configured to perform a diamond growth reaction. Inside the reaction chamber 1, there is a molybdenum substrate 2, a multi-channel current control module 4, an infrared temperature measurement module 5, and a substrate 6 to be grown.

[0028] The substrate 6 to be grown is placed on top of the molybdenum abutment 2. The substrate 6 can be a diamond seed or a silicon wafer. The substrate 6 can be fixed by mechanical clamps or placed directly on the surface of the molybdenum abutment 2 by gravity.

[0029] A distributed magnetic induction coil group 3 is provided at the bottom of the molybdenum base 2. This coil group 3 can consist of multiple independent electromagnetic coils, which are arranged below or inside the molybdenum base 2. Specifically, there are two arrangement schemes: Option 1 (Concentric Circle Partition): Divide the base radially into N concentric ring regions (N≥2, adapted according to the base size). Each region independently embeds a set of coils. The number of coil turns increases with the region radius (inner ring 5-10 turns, middle ring 10-15 turns, outer ring 15-20 turns). The coil axis is perpendicular to the base surface, and the embedding depth is 5-10mm from the base surface (to avoid interfering with plasma discharge). Option 2 (Uniform Distribution): M groups of coils are evenly arranged along the surface of the base in a matrix (such as 3×3, 4×4) or equilateral triangle array (M≥4, spacing = base diameter / (M^(1 / 2)+1)), with a uniform number of turns of 6-10 turns per group of coils, and the embedding depth is the same as that of Option 1; The multi-channel current regulation module 4 is electrically connected to the distributed magnetic induction coil group 3. This module 4 is configured to provide independent current to each coil or group of coils in the coil group 3. For example, the module 4 can be a power supply system containing multiple independent power output channels, the current output of each channel of which can be manually adjusted to control the magnetic field strength of the corresponding coil.

[0030] Infrared temperature measurement module 5 is installed on the side wall of reaction chamber 1. The function of module 5 is to collect the temperature distribution characteristics of the diamond above the base in real time.

[0031] The following example will provide a more detailed explanation of the above technical solution: In an MPCVD diamond growth experiment, a diamond film of uniform thickness needs to be prepared on a large-sized substrate 6. First, the substrate 6 is placed on a molybdenum stage 2, which is installed inside a reaction chamber 1. A distributed magnetic induction coil group 3 is pre-embedded at the bottom of the molybdenum stage 2. Each coil of this coil group 3 is electrically connected to a multi-channel current control module 4 outside the reaction chamber 1 via wires. Simultaneously, an infrared temperature measurement module 5 is fixed to the side wall of the reaction chamber 1, and its field of view is adjusted to monitor the entire surface temperature of the substrate 6.

[0032] At the start of the diamond growth process, reaction chamber 1 is evacuated and a mixture of methane and hydrogen reactant gases is introduced. The microwave source is activated, exciting the reactant gases to form plasma. At this time, due to the inherent characteristics of the microwave field, the plasma may exhibit a radial distribution above the substrate 6 to be grown, with a high density in the central region and a low density in the edge region. This results in a temperature difference between the center and the edge of the substrate, which in turn affects the uniformity of diamond growth.

[0033] To address this issue, the distributed magnetic induction coil group 3 is activated. The multi-channel current regulation module 4 supplies current to each coil in the coil group 3.

[0034] During the control process, the infrared temperature measurement module 5 continuously collects temperature distribution data on the surface of the substrate 6 to be grown in real time. This temperature data is used to assess the uniformity of the plasma. For example, if the infrared temperature measurement module 5 detects that the temperature of the edge region of the substrate is lower than that of the center region, it indicates that the edge plasma density may be insufficient. At this time, the multi-channel current control module 4 can automatically or manually increase the current of the corresponding edge coil according to a preset control strategy, thereby increasing the temperature of the edge plasma.

[0035] In this way, driven by the multi-channel current control module 4, the distributed magnetic induction coil group 3 can dynamically and precisely control the radial distribution of the plasma based on the real-time temperature feedback provided by the infrared temperature measurement module 5. The various components of the device work closely together: the reaction chamber 1 provides a controlled environment, the molybdenum base 2 supports the substrate and works in conjunction with the coil group 3, the coil group 3 generates a magnetic field, the multi-channel current control module 4 achieves precise control of the magnetic field, and the infrared temperature measurement module 5 provides crucial feedback information. Ultimately, all these components work together to act on the plasma on the substrate 6 to be grown, achieving higher uniformity throughout the growth area, thereby obtaining diamond material with consistent thickness and excellent quality.

[0036] Based on the above examples, the apparatus provided in this embodiment demonstrates a significant technical contribution in solving the problem of plasma uniformity in the growth of large-size diamonds using MPCVD.

[0037] In existing technologies, plasma uniformity control mainly relies on microwave power adjustment, reactive gas ratio optimization, or cavity structure modification. However, these methods have inherent limitations in large-size substrate applications. For example, microwave power adjustment often simultaneously affects the diamond growth rate, making it difficult to optimize uniformity independently without sacrificing growth efficiency; the range of gas ratio control is limited, and the ability to finely control the spatial distribution of plasma is insufficient; while cavity structure modification involves high costs and poor compatibility.

[0038] In contrast, this embodiment provides a novel, non-invasive method for controlling plasma space by incorporating a distributed magnetic induction coil group 3 at the bottom of the molybdenum substrate 2, combined with a multi-channel current control module 4 and an infrared temperature measurement module 5. In the example above, when the infrared temperature measurement module 5 detects that the temperature of the edge region of the substrate 6 to be grown is too low, the multi-channel current control module 4 can precisely adjust the current of the corresponding edge coil, thereby locally enhancing the magnetic field in that region. This local magnetic field can effectively confine or guide the edge plasma, increasing its density and temperature, thus compensating for the inherent radial distribution difference of microwave plasma, characterized by "high density at the center and low density at the edge."

[0039] This distributed magnetic field control-based scheme avoids direct and significant intervention in microwave power or gas ratios, thus enabling precise and localized control of plasma uniformity without significantly affecting the growth rate and overall process parameters. Furthermore, the device offers high control flexibility, allowing for both open-loop control based on preset process parameters and closed-loop dynamic adjustment using real-time feedback from the infrared temperature measurement module 5. This allows for rapid adaptation to different substrate sizes and diverse diamond growth process requirements. This technological concept fundamentally solves the uniformity problem of plasma spatial confinement in existing technologies, providing effective technical support for the industrial application of large-size, high-quality diamonds.

[0040] In some other embodiments, this application proposes a device for controlling plasma homogeneity in MPCVD using a distributed magnetic field, comprising a reaction chamber 1 and a molybdenum stage 2, a multi-channel current control module 4, an infrared temperature measurement module 5, and a substrate 6 to be grown, all disposed within the reaction chamber 1. The substrate 6 is placed on the molybdenum stage 2, and a distributed magnetic induction coil group 3 is provided at the bottom of the molybdenum stage 2. The multi-channel current control module 4 is electrically connected to the distributed magnetic induction coil group 3, and the infrared temperature measurement module 5 is installed on the side wall of the reaction chamber 1 to collect the real-time temperature distribution characteristics of the diamond above the stage. However, in practical applications, if the arrangement of the distributed magnetic induction coil group 3 is improper, it may be difficult to achieve fine control of the plasma distribution, thereby affecting the uniformity of diamond growth.

[0041] In this regard, this application further proposes that the distributed magnetic induction coil group 3 of the aforementioned device includes several groups of concentric coils. This technical feature refers to the configuration of the distributed magnetic induction coil group 3, which is not a single coil but consists of multiple groups of coils arranged in a concentric circle. This arrangement allows the magnetic field to exhibit gradient or regional characteristics in the radial direction, thereby achieving precise control of the plasma distribution. One implementation is that these concentric coils can be in the form of flat helical coils, directly embedded or attached to the bottom of the molybdenum base 2. Another implementation is that these concentric coils can be composed of multiple layers of windings to increase the magnetic field strength, and each group of coils can be independently powered to facilitate individual adjustment of its generated magnetic field.

[0042] The proposed solution utilizes a distributed magnetic induction coil group 3, designed as several concentric coils, to achieve radial regional magnetic field control over the plasma region above the molybdenum substrate 2. When the multi-channel current control module 4 supplies current to these concentric coils, each coil generates a magnetic field centered on its own center. Because these coils are arranged concentrically, their generated magnetic fields exhibit different magnetic field strength distributions in the radial direction. For example, the inner coils primarily affect the plasma in the central region, while the outer coils primarily affect the plasma in the edge regions. This regional magnetic field control capability allows the device to selectively adjust the magnetic field strength in different radial regions based on the real-time diamond temperature distribution characteristics acquired by the infrared temperature measurement module 5. This more effectively suppresses plasma inhomogeneity, avoids localized overheating or growth rate differences caused by improper magnetic field distribution, and ultimately promotes uniform diamond growth.

[0043] The following example illustrates this: the distributed magnetic induction coil group 3 can consist of three concentric circular coils. The innermost coil can be designed as a small-diameter circular coil with a moderate number of turns, used to control the plasma in the central region of the molybdenum substrate 2. The middle coil can have a larger diameter and more turns to cover and control the plasma in the central region of the molybdenum substrate 2. The outermost coil can have the largest diameter and the most turns, used to control the plasma in the edge region of the molybdenum substrate 2. These coils can be wound with high-conductivity copper wire or copper tubing and encapsulated with insulating material to ensure stable operation in high-temperature and plasma environments. Each coil group is connected to the multi-channel current control module 4 via an independent circuit, thereby enabling independent adjustment of the current in each coil group.

[0044] Through the above technical solution, the device of this application can achieve radial regional fine-tuning of the plasma distribution within the MPCVD reaction chamber 1. This structure allows the magnetic field to be locally adjusted according to the actual temperature distribution of the diamond growth region on the molybdenum substrate 2, effectively compensating for the radial non-uniformity of the plasma, thereby significantly improving the uniformity of diamond growth and increasing product quality and yield.

[0045] In this regard, such as Figure 2 As shown, this application further proposes that the molybdenum base 2 be divided into three concentric annular regions along the radial direction, namely the inner ring, the middle ring, and the outer ring, with 5-10 turns, 10-15 turns, and 15-20 turns of coil embedded in the inner ring, the middle ring, and the outer ring, respectively.

[0046] Specifically, the entire radial range of the molybdenum abutment 2 is precisely divided into three independent, continuous concentric ring regions, rather than an arbitrary number of regions. This division aims to provide a balanced granularity of magnetic field control, achieving sufficiently fine control while avoiding overly complex coil layouts and control systems. This division ensures that the magnetic field strength can be independently and effectively adjusted at different radial positions of the abutment 2 to address radial inhomogeneities of the plasma. These three concentric ring regions are explicitly named the inner ring, middle ring, and outer ring to clearly define their relative radial positions. The inner ring typically refers to the portion closest to the center of the abutment 2, the outer ring to the portion closest to the edge of the abutment 2, and the middle ring in between. This naming convention facilitates the identification and management of different regions during design, manufacturing, and operation, ensuring that the coils in each region can be accurately positioned and controlled. Furthermore, specific ranges of coil turns are set for each specific concentric ring region (inner ring, middle ring, outer ring). The inner ring contains 5-10 turns of coil, the middle ring contains 10-15 turns of coil, and the outer ring contains 15-20 turns of coil. This incremental turns design aligns with the principle of "coil turns increasing with the region radius" in the aforementioned technical solution, but provides more specific numerical constraints. By configuring coils with different turns ranges for different radial regions, the magnetic field strength of each region can be more precisely adjusted locally while maintaining the overall magnetic field gradient trend. For example, increasing the number of turns in the outer coil can enhance the magnetic field in the edge region, thereby affecting the plasma density and temperature in that region to compensate for the edge effects commonly found in MPCVD reactors. This turns configuration allows the magnetic field control module 4 to more effectively generate the desired magnetic field distribution to optimize plasma uniformity.

[0047] The proposed solution divides the molybdenum substrate 2 radially into three concentric annular regions: an inner ring, a middle ring, and an outer ring. Each region is configured with a specific range of coil turns, enabling the distributed magnetic induction coil group 3 to generate a more refined and controllable radial magnetic field gradient. In MPCVD processes, plasma density and temperature typically exhibit radial inhomogeneity. This specific three-region division and turns configuration allows the system to generate a magnetic field that gradually intensifies from the inside out, providing sufficient flexibility and precision to address the common radial inhomogeneity issues in MPCVD reactors while maintaining controllable system complexity. The multi-channel current control module 4 can independently adjust the coil current in different regions based on the real-time temperature distribution acquired by the infrared temperature measurement module 5, thereby precisely controlling the magnetic field strength in each region. This precise magnetic field control effectively influences the spatial distribution of plasma, electron energy, and active particle transport, thereby compensating for the radial inhomogeneity of plasma and temperature and ensuring a uniform growth environment on the surface of the substrate 6 to be grown.

[0048] To address this, this application further proposes that the embedding depth of the distributed magnetic induction coil group 3 be 5-10 mm from the surface of the molybdenum base 2. Here, "embedding depth" refers to the vertical position of the distributed magnetic induction coil group 3 inside the molybdenum base 2, specifically the distance between the top surface of the coil group 3 and the surface of the molybdenum base 2. This distance is crucial for the interaction between the magnetic field and the plasma. If the embedding depth is too large, the magnetic field strength will significantly attenuate in the plasma region, resulting in a weakened ability to control the plasma; if the embedding depth is too small, it may cause the coil group 3 to overheat, even affecting the stability and uniformity of the plasma. Limiting this depth to the range of 5-10 mm aims to ensure that the magnetic field can effectively act on the plasma region, while also considering the heat dissipation and protection of the coil group 3. Achieving this embedding depth can be achieved in two ways: One method involves pre-machining grooves or cavities of a specific depth at the bottom of the molybdenum base 2, precisely placing the distributed magnetic induction coil assembly 3 into these grooves or cavities, and fixing and sealing it by filling with high-temperature resistant insulating material or welding a cover plate, ensuring that the top surface of the coil assembly 3 maintains a distance of 5-10 mm from the base surface of the molybdenum base 2. Another method is to employ a multi-layered structure design for the molybdenum base 2, embedding the distributed magnetic induction coil assembly 3 in a sandwich-like manner within the molybdenum material during manufacturing. By precisely controlling the thickness of each layer, the distance between the top surface of the coil assembly 3 and the base surface of the final molybdenum base 2 is maintained within the range of 5-10 mm.

[0049] The solution proposed in this application effectively solves the balance problem between magnetic field control effect and thermal stability by precisely controlling the embedding depth of the distributed magnetic induction coil group 3 within a range of 5-10 mm from the surface of the molybdenum base 2. In the above embodiment, the distributed magnetic induction coil group 3 is designed as several sets of concentric coils, and is divided into multiple concentric ring regions radially along the molybdenum base 2. Each region independently embeds a set of coils, and the number of coil turns increases with the increase of the region radius. This radially distributed coil design, combined with the precise embedding depth, allows the magnetic field generated by the coil group 3 to act on the plasma region above the molybdenum base 2 with optimal strength and distribution. If the embedding depth exceeds this range, the effect of the magnetic field on the plasma will be greatly reduced, and it will be impossible to effectively achieve fine control of plasma density and temperature. By placing the coil group 3 at a depth of 5-10 mm, it is ensured that the magnetic field can penetrate the molybdenum base 2 and effectively affect the trajectory of charged particles in the plasma, thereby achieving control of plasma uniformity, while avoiding excessive heat load on the coil group 3 due to being too close to the plasma, ensuring the long-term stable operation of the device. This combination of depth control and radial coil distribution enables the device to more precisely shape plasma morphology and optimize the diamond growth environment.

[0050] In some other embodiments, this application proposes a device for controlling plasma homogeneity in MPCVD using a distributed magnetic field. The device includes a reaction chamber 1 and a molybdenum stage 2, a multi-channel current control module 4, an infrared temperature measurement module 5, and a substrate 6 to be grown, all disposed within the reaction chamber 1. The substrate 6 is placed on the molybdenum stage 2, and a distributed magnetic induction coil group 3 is located at the bottom of the molybdenum stage 2. The multi-channel current control module 4 is electrically connected to the distributed magnetic induction coil group 3. The infrared temperature measurement module 5 is installed on the side wall of the reaction chamber 1 to collect real-time data on the diamond temperature distribution above the stage. However, in actual diamond growth processes, plasma distribution is often affected by various factors, potentially leading to localized non-uniformity. This results in uneven temperature distribution of the diamond on the substrate 6, thus affecting the growth quality and uniformity of the diamond. Traditional magnetic field control methods may struggle to achieve precise and localized control of plasma distribution, thereby limiting further improvements in diamond growth uniformity.

[0051] In this regard, this application further proposes that the distributed magnetic induction coil group 3 includes M groups of coils uniformly arranged in a matrix or equilateral triangular array along the surface of the molybdenum substrate 2. The distributed magnetic induction coil group 3 is the core component for generating a magnetic field to regulate plasma homogeneity. Its function is to generate a magnetic field through current, thereby affecting the density, distribution, and energy of the plasma, to achieve regulation of the temperature and plasma homogeneity in the diamond growth region. Besides the coil form described in this application, the distributed magnetic induction coil group 3 can also be other structures capable of generating a controllable local magnetic field, such as multiple independent electromagnet arrays, or a magnetic core structure using a variable permeability material, with its magnetic field distribution changed by external control. The uniform arrangement of M groups of coils in a matrix or equilateral triangular array along the surface of the molybdenum substrate 2 describes the specific arrangement of the distributed magnetic induction coil group 3. A matrix arrangement refers to the coil groups being arranged in rows and columns to form a rectangular grid. This arrangement provides a regular and predictable magnetic field distribution, facilitating independent control of different areas. For example, this can be understood as forming a two-dimensional coil grid below the molybdenum base 2, with each grid point or region corresponding to a set of coils. A uniformly arranged equilateral triangular array refers to the coil groups being arranged with the vertices or centers of equilateral triangles as units, forming a dense, uniformly covering array. This arrangement may provide more precise local magnetic field control compared to a matrix arrangement, especially in scenarios requiring isotropic magnetic field control. For example, this can be understood as forming a grid composed of multiple equilateral triangles below the molybdenum base 2, with a set of coils placed at the center or vertex of each triangle. M sets of coils indicate that the distributed magnetic induction coil group 3 consists of M independent coil units or coil groups. The arrangement of M sets of coils makes magnetic field control localized and controllable; each group of coils can generate a magnetic field independently or collaboratively, thereby achieving fine adjustment of the plasma distribution. M sets of coils can consist of independent coils or multiple coils connected in series or parallel to form a controllable unit.

[0052] The scheme of this application arranges M groups of coils in a matrix or equilateral triangular array uniformly along the surface of the molybdenum substrate 2 using a distributed magnetic induction coil group 3. This makes the magnetic field below the molybdenum substrate 2 no longer a single, monolithic entity, but rather divided into multiple independently or collaboratively controllable regions. After the plasma in the MPCVD reaction chamber 1 is excited, the infrared temperature measurement module 5 collects the temperature distribution of the diamond on the substrate 6 to be grown in real time. If uneven temperature distribution is detected, such as a region being too hot or too cold, the multi-channel current control module 4 can precisely adjust the current of the M groups of coils in the corresponding region according to a preset control strategy. By changing the current of a specific coil group, the magnetic field strength in that region can be locally enhanced or weakened, thereby affecting the plasma density, electron temperature, and ion flux in that region. For example, enhancing the magnetic field can confine the plasma, making it more concentrated, thus increasing the local temperature; weakening the magnetic field may allow the plasma to diffuse, reducing the local temperature. The uniform arrangement of matrix or equilateral triangular arrays ensures the coverage and control of the magnetic field across all areas of the molybdenum substrate 2 surface, avoiding blind spots in control. This enables precise and localized control of the plasma uniformity across the entire substrate 6 to be grown, effectively solving the problem of diamond growth temperature differences caused by uneven plasma distribution. This independent control mechanism of multiple coils allows the device to dynamically and regionally adjust the magnetic field based on real-time temperature feedback, thereby maintaining a high degree of plasma uniformity.

[0053] The following is a concrete example illustrating this: the distributed magnetic induction coil group 3 can consist of M independent coil units arranged in a matrix along the surface of the molybdenum substrate 2. For example, a 3x3 coil array, i.e., M=9 coil units, can be placed below the molybdenum substrate 2. Each coil unit can be an independent circular or square coil, and its number of turns and wire diameter can be designed according to the required magnetic field strength and current carrying capacity. These coils are fixed to the bottom of the molybdenum substrate 2 with insulating material and electrically connected to the independent channels of the multi-channel current control module 4. When the infrared temperature measurement module 5 detects that the temperature in the central region of the substrate 6 is too high while the temperature in the edge region is too low, the multi-channel current control module 4 can reduce the current of the coil unit corresponding to the central region and increase the current of the coil unit corresponding to the edge region. Alternatively, the distributed magnetic induction coil group 3 can also be arranged in an equilateral triangular array. For example, M coil units can be evenly distributed in a honeycomb structure below the molybdenum substrate 2, with the center point of each coil unit forming an equilateral triangular grid. This arrangement can provide denser magnetic field coverage and smoother magnetic field gradient changes, making it suitable for applications requiring extremely high plasma uniformity.

[0054] By employing the aforementioned technical solution, M groups of coils are uniformly arranged in a matrix or equilateral triangular array along the surface of the molybdenum substrate 2 using a distributed magnetic induction coil group 3. This allows for precise and localized control of the plasma distribution within the MPCVD reaction chamber 1. This multi-region, independently controlled magnetic field structure enables the device to precisely adjust the magnetic field strength in different regions based on the real-time diamond temperature distribution characteristics acquired by the infrared temperature measurement module 5, using a multi-channel current control module 4. This effectively solves the problem of localized plasma inhomogeneity, which is difficult to address with traditional single or simple ring coils, significantly improving the temperature uniformity of diamond growth on the substrate 6, thereby contributing to the acquisition of higher quality and more uniform diamond films.

[0055] In some embodiments described above in this application, a distributed magnetic induction coil group 3 is proposed, comprising M groups of coils uniformly arranged in a matrix or equilateral triangular array along the surface of the molybdenum base 2. However, in practical applications, if the number of coil groups M is too small, or the number of turns of a single coil group is inappropriate, it may lead to insufficient precision in magnetic field control, which may not be able to effectively cope with the local non-uniformity of plasma distribution, thereby affecting the uniformity of diamond growth.

[0056] In this regard, this application further proposes that the number of coil groups M is greater than or equal to four, and the number of turns of a single coil group is 6-10 turns.

[0057] The number of coil groups M is greater than or equal to four, meaning that there are at least four groups of independent coil units evenly arranged in a matrix or equilateral triangular array along the surface of the molybdenum base 2. This increases the precision and coverage of magnetic field control, making it possible to more accurately control the local magnetic field of the plasma region. For example, this can be achieved by evenly distributing at least four independent coil units at the bottom of the molybdenum base 2, such as setting one group of coils at each of the four corners or center and symmetrically around the perimeter of the base; or, it can be achieved by dividing the surface of the molybdenum base 2 into at least four regions, with each region corresponding to a group of coils, ensuring that each region can independently generate a magnetic field. The number of turns in a single coil group is 6-10 turns, meaning that the number of turns of the wire winding constituting each independent coil unit is between 6 and 10. The number of turns directly affects the magnetic field strength generated by the coil. Setting the number of turns to 6-10 turns can provide sufficient magnetic field strength to effectively control the local plasma while ensuring the compactness of the coil structure. For example, the number of turns in each coil group can be precisely controlled during coil manufacturing to be between 6 and 10 turns, such as using 7 or 8 turns; or, different specifications of wire or winding process can be selected to ensure that each coil group can stably achieve a winding of 6 to 10 turns within a given space, while ensuring that its electrical and heat dissipation performance meets the requirements.

[0058] The proposed solution sets the number of coil groups M in the distributed magnetic induction coil group 3 to be greater than or equal to four, and ensures that the number of turns in a single coil group is 6-10. This results in a sufficient number of independent magnetic field control units distributed on the surface of the molybdenum substrate 2, enabling more precise and localized control of the magnetic field distribution in the plasma region. Simultaneously, setting the number of turns in a single coil group to 6-10 ensures that each independent coil unit can generate a sufficiently strong magnetic field when energized, effectively influencing the plasma behavior within its coverage area. By using the multi-channel current control module 4 to independently or collaboratively adjust the current of these sufficient coil groups with appropriate magnetic field strength, the local magnetic field strength and distribution can be precisely adjusted based on the real-time diamond temperature distribution characteristics acquired by the infrared temperature measurement module 5. For example, in areas with lower temperatures, the current of the corresponding coil group can be appropriately increased, thereby strengthening the magnetic field in that area, altering the plasma transport characteristics, increasing plasma density or energy, and thus raising the local temperature. Conversely, in areas with higher temperatures, the current of the corresponding coil group can be reduced. This refined, locally controllable magnetic field regulation capability effectively compensates for the problems of uneven magnetic field coverage or insufficient regulation precision that may result from relying solely on macroscopic arrangement methods. As a result, it can more effectively regulate the plasma uniformity in MPCVD, ensuring a more uniform temperature and plasma distribution during the diamond growth process.

[0059] The following is a concrete example illustrating this: the distributed magnetic induction coil group 3 can consist of M independent coil groups, where M can be 6. These coil groups can be evenly arranged in an equilateral triangular array at the bottom of the molybdenum substrate 2, for example, a central coil group surrounded by five coil groups. The number of turns in each coil group can be specifically set to 7 turns. In actual operation, when the infrared temperature measurement module 5 detects temperature non-uniformity on the surface of the substrate 6 to be grown, for example, a region with a low temperature, the multi-channel current control module 4 can increase the current of the coil group corresponding to the low-temperature region from the initial 3A to 3.5A to enhance the magnetic field strength in that region. At the same time, for regions with a high temperature, the current of the corresponding coil group can be appropriately reduced, for example, from 3A to 2.5A. In this way, precise adjustment of the local magnetic field can be achieved, thereby optimizing the distribution and energy of the plasma, ultimately achieving a uniform diamond growth temperature.

[0060] By setting the number of coil groups M in the distributed magnetic induction coil group 3 to be greater than or equal to four, and ensuring that the number of turns in a single coil group is 6-10 turns, the device of this application can significantly improve the precision and effectiveness of plasma magnetic field control within the MPCVD reaction chamber 1. A sufficient number of coil groups provides a wider magnetic field coverage and more refined local control capabilities, avoiding the problems of magnetic field blind spots or coarse control caused by insufficient coil numbers. Simultaneously, an appropriate number of coil turns ensures that each coil group can generate a sufficiently strong magnetic field to effectively influence plasma behavior. This combination enables the device to precisely and dynamically adjust the local magnetic field through the multi-channel current control module 4 based on the real-time temperature distribution feedback from the infrared temperature measurement module 5, thereby more effectively eliminating plasma inhomogeneity and ensuring a more uniform diamond growth temperature and plasma density distribution on the substrate 6, ultimately improving the quality and consistency of diamond growth.

[0061] In some embodiments described above, a distributed magnetic induction coil group 3 is proposed, comprising M groups of coils uniformly arranged in a matrix or equilateral triangular array along the surface of the molybdenum substrate 2, with the number of coil groups M being greater than or equal to four, and the number of turns in a single coil group being 6-10 turns. However, in practical applications, how to accurately determine the spacing between these M groups of coils to ensure the uniformity and effectiveness of the magnetic field distribution, thereby achieving precise control of plasma uniformity, is a problem that needs to be solved. Improper coil spacing may lead to uneven magnetic field distribution, which in turn affects the temperature uniformity of diamond growth.

[0062] In response, this application further proposes a formula for calculating the spacing of the M groups of coils:

[0063] In the formula: m is the spacing; d is the diameter along the molybdenum base; M is the number of coil groups.

[0064] This calculation formula provides a quantitative method for determining the spacing between M groups of coils in a distributed magnetic induction coil group 3. Its function is to mathematically correlate the coil arrangement density with the size of the molybdenum base 2 and the number of coil groups, thereby ensuring a uniform distribution of the magnetic field across the entire surface of the molybdenum base 2. This formula can be pre-integrated into the control algorithm of the multi-channel current control module 4 to guide the physical arrangement of the coils, or used as a basis for coil layout during the device design phase. Furthermore, this formula can also be implemented through a software module, automatically calculating the optimal coil spacing based on the input diameter of the molybdenum base 2 and the number of coil groups M. Here, the spacing m refers to the distance between the centers of two adjacent groups of coils in the distributed magnetic induction coil group 3. Precise setting of this spacing is crucial for achieving a uniform magnetic field distribution. For example, in a matrix arrangement, m can refer to the row spacing or column spacing; in an equilateral triangle array, m can refer to the shortest distance between the centers of adjacent coils. The diameter d refers to the diameter of the effective area on the molybdenum base 2 used for coil arrangement. This parameter is the fundamental dimension for calculating the coil spacing, reflecting the physical range that the magnetic field needs to cover. For example, d can be the actual physical diameter of the molybdenum substrate 2, or the diameter of the effective growth region determined according to process requirements. The number of coil groups M refers to the total number of independently controlled coil units in the distributed magnetic induction coil group 3. The value of M directly affects the precision and coverage of magnetic field control. For example, M can be selected based on the size of the molybdenum substrate 2 and the required magnetic field resolution; generally, the larger M is, the higher the precision of magnetic field control.

[0065] This application provides a formula for calculating the spacing of M groups of coils, making the arrangement of the distributed magnetic induction coil group 3 more scientific and precise. During the device preprocessing stage, the spacing m of the M groups of coils is determined using this formula based on the diameter d of the molybdenum base 2 and the preset number of coil groups M. This quantitative arrangement method based on size and quantity ensures that the distributed magnetic induction coil group 3 can form a highly uniform initial magnetic field distribution at the bottom of the molybdenum base 2. When the microwave source starts to excite the plasma, this uniform initial magnetic field can effectively guide and confine the plasma, resulting in a more uniform density and temperature distribution above the substrate 6 to be grown. Compared to relying solely on experience or simple uniform arrangement, the spacing determined by this formula can more effectively avoid areas with excessively strong or weak local magnetic fields, thereby reducing the temperature gradient caused by plasma inhomogeneity. In subsequent dynamic control, the multi-channel current control module 4 can make more precise adjustments based on this optimized initial magnetic field distribution, further improving temperature uniformity and reducing the complexity and response time of the control. Therefore, the introduction of this spacing calculation formula fundamentally optimizes the layout of the magnetic field source, providing a solid foundation for achieving plasma and temperature uniformity in the MPCVD process.

[0066] In other embodiments, this application proposes a method for controlling plasma uniformity in MPCVD using a distributed magnetic field. During MPCVD diamond growth, plasma uniformity and the temperature distribution of the abutment are crucial to the quality and growth efficiency of the diamond film. However, in practice, due to the influence of various factors such as microwave coupling, gas flow, and heat conduction, it is often difficult to maintain a high degree of plasma uniformity, and radial temperature gradients easily appear on the abutment surface, leading to uneven diamond growth and even defects.

[0067] In this regard, this application further proposes a method comprising the following steps: Step 1: Device pretreatment; embed the coil group into the base according to the preset scheme, connect the multi-channel current control module 4, and calibrate the infrared temperature measurement module 5; then put the molybdenum base 2 into the reaction chamber 1, seal it, and evacuate it to a vacuum degree of 1-5 Pa through the vacuum system, and introduce a mixture of methane and hydrogen reaction gas. Step 2: Coil initialization; Select the layout scheme according to the base size, and set the initial current of each group of coils to 3-3.5A through the multi-channel current control module 4; Step 3: Plasma excitation; Start the microwave source at a frequency of 2.45 GHz to excite the reactive gas to form plasma, gradually increase the microwave power to 6~8 kW and the gas pressure to around 15 kPa to reach the target temperature for diamond growth; Step 4: Dynamic control of magnetic field; Open-loop mode: The initial current is continuously maintained or the current is adjusted according to the growth stage based on the preset process parameters; Closed-loop mode: The infrared temperature monitoring module collects the temperature distribution of different points in the radial direction of the diamond in real time. If the temperature difference exceeds 50°C, the multi-channel current control module 4 automatically adjusts the coil current in the corresponding area until the temperature difference is less than or equal to 50°C.

[0068] The device pretreatment in step one aims to provide a stable and controlled environment for diamond growth. Embedding the coil group into the base according to a pre-defined scheme involves selecting a suitable arrangement of the distributed magnetic induction coil group 3, such as concentric rings or a matrix, based on the size and shape of the molybdenum base 2, and firmly integrating it to the bottom of the molybdenum base 2 to ensure effective magnetic field control. Connecting the multi-channel current control module 4 enables independent and precise control of the current in each coil group. Calibrating the infrared temperature measurement module 5 ensures accurate acquisition of the temperature information of the substrate 6 to be grown during subsequent growth. Installing and sealing the molybdenum base 2 into the reaction chamber 1 maintains the airtightness of the reaction chamber 1 during vacuuming, preventing the entry of external impurity gases. Evacuating to a vacuum level of 1-5 Pa removes residual gases and impurities from the reaction chamber 1, creating conditions for the subsequent introduction of high-purity reaction gases.

[0069] The coil initialization in step two is to establish a basic magnetic field environment before plasma excitation. Selecting the coil arrangement based on the substrate size means choosing the coil arrangement that best covers the surface of the molybdenum substrate 2, according to its specific dimensions and shape. Setting the initial current of each group of coils to 3-3.5A via the multi-channel current control module 4 provides a preset magnetic field distribution in the early stages of growth, which helps in the stable formation of plasma and initial temperature uniformity.

[0070] Step three, plasma excitation, is the core step in diamond growth. Starting the microwave source at 2.45 GHz provides energy to ionize the methane and hydrogen mixture in reaction chamber 1, forming plasma. Gradually increasing the microwave power to 6-8 kW and the gas pressure to around 15 kPa ensures the plasma is steadily heated to the optimal temperature for diamond growth and maintains a stable plasma density. Reaching the target diamond growth temperature means heating the substrate 6 to be grown to the optimal temperature range for diamond crystal growth.

[0071] The dynamic control of the magnetic field in step four is crucial for achieving plasma uniformity and temperature control. In open-loop mode, the initial current is continuously maintained or the current is adjusted according to the growth stage based on preset process parameters. This is suitable for scenarios where process conditions are relatively stable or predictable, and control is achieved through a pre-set current curve. Closed-loop mode introduces a real-time feedback mechanism. The infrared temperature monitoring module 5 collects the temperature distribution at different radial points on the diamond in real time. If a temperature difference exceeds 50°C, the multi-channel current control module 4 automatically adjusts the current in the corresponding coil area until the temperature difference is less than or equal to 50°C. This real-time feedback and automatic adjustment mechanism effectively addresses temperature non-uniformity during growth, ensuring a stable diamond growth environment.

[0072] The present application's solution organically combines the distributed magnetic induction coil group 3 with the multi-channel current control module 4 and the infrared temperature measurement module 5 through the above steps, forming a closed-loop control system. In the device pretreatment stage, a clean and stable initial environment is created for diamond growth. In the coil initialization stage, a basic magnetic field is established, laying the foundation for plasma excitation. After plasma excitation, active particles required for diamond growth are generated through microwave energy. In the magnetic field dynamic control stage, the distributed magnetic induction coil group 3, under the control of the multi-channel current control module 4, can generate a locally adjustable magnetic field, which can affect the electron density, energy distribution, and heat exchange efficiency between the plasma and the substrate. The infrared temperature measurement module 5 monitors the temperature distribution of the substrate 6 to be grown in real time and feeds the temperature data back to the multi-channel current control module 4. When temperature non-uniformity is detected (e.g., a temperature difference exceeding 50°C), the multi-channel current control module 4 automatically adjusts the current of the coil in the corresponding area according to a preset control strategy, thereby changing the local magnetic field strength and thus regulating the plasma characteristics and heat flow in that area to eliminate temperature gradients and make the surface temperature of the substrate 6 to be grown more uniform. This dynamic, regional magnetic field control capability enables precise control of plasma uniformity and substrate temperature distribution during diamond growth, effectively solving the uniformity challenge faced by traditional MPCVD equipment when growing large-size or high-quality diamond films.

[0073] The above technical solution enables precise and dynamic control of plasma uniformity within the MPCVD reaction chamber 1 and temperature distribution on the molybdenum substrate 2. Through pretreatment, initialization, excitation, and dynamic control steps, particularly the introduction of both open-loop and closed-loop magnetic field control modes, the temperature distribution during diamond growth can be effectively controlled. The real-time temperature feedback and automatic current adjustment mechanism in the closed-loop mode can promptly respond to temperature non-uniformity issues that arise during growth, avoiding growth defects caused by localized overheating or undercooling. This significantly improves the uniformity and quality of diamond film growth and enhances growth efficiency.

[0074] The above description is not intended to limit the present invention in any way. Although the present invention has been disclosed through the above embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some changes or modifications to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A device for controlling plasma homogeneity in MPCVD using a distributed magnetic field, characterized in that, The system includes a reaction chamber (1) and a molybdenum stage (2), a multi-channel current control module (4), an infrared temperature measurement module (5), and a substrate (6) to be grown, all located within the reaction chamber (1). The substrate (6) to be grown is placed on the molybdenum stage (2). A distributed magnetic induction coil group (3) is provided at the bottom of the molybdenum stage (2). The multi-channel current control module (4) is electrically connected to the distributed magnetic induction coil group (3). The infrared temperature measurement module (5) is installed on the side wall of the reaction chamber (1) to collect the temperature distribution characteristics of the diamond above the stage in real time.

2. The device for controlling plasma homogeneity in MPCVD using a distributed magnetic field according to claim 1, characterized in that, The distributed magnetic induction coil group (3) includes several groups of concentric coils.

3. The device for controlling plasma homogeneity in MPCVD using a distributed magnetic field according to claim 2, characterized in that, The coils of the several sets of concentric circles are divided into N concentric ring regions along the molybdenum base (2) radially. Each region independently embeds a set of coils. The number of coil turns increases with the increase of the region radius. The coil axis is perpendicular to the surface of the base.

4. The device for controlling plasma homogeneity in MPCVD using a distributed magnetic field according to claim 3, characterized in that, The molybdenum base (2) is divided into three concentric ring regions along the radial direction, namely the inner ring, the middle ring and the outer ring, and the inner ring, the middle ring and the outer ring are respectively embedded with 5-10 turns, 10-15 turns and 15-20 turns of coil.

5. The device for controlling plasma homogeneity in MPCVD using a distributed magnetic field according to claim 4, characterized in that, The embedding depth of the distributed magnetic induction coil group (3) is 5-10 mm from the surface of the molybdenum abutment (2).

6. The device for controlling plasma homogeneity in MPCVD using a distributed magnetic field according to claim 1, characterized in that, The distributed magnetic induction coil group (3) includes M groups of coils evenly arranged in a matrix or equilateral triangle array along the surface of the molybdenum base (2).

7. The device for controlling plasma homogeneity in MPCVD using a distributed magnetic field according to claim 6, characterized in that, The number of coil groups M is greater than or equal to four, and the number of turns in a single coil group is 6-10 turns.

8. The device for controlling plasma homogeneity in MPCVD using a distributed magnetic field according to claim 7, characterized in that, The formula for calculating the spacing of the M groups of coils is: In the formula: m For spacing; d The diameter is along the molybdenum abutment; M This represents the number of coil groups.

9. A method for controlling plasma homogeneity in MPCVD using a distributed magnetic field, characterized in that, This method uses the device described in any one of claims 1-8 for controlling plasma homogeneity in MPCVD using a distributed magnetic field, and the specific steps are as follows: Step 1: Equipment Pretreatment; The coil assembly is embedded inside the base according to the preset scheme, connected to the multi-channel current control module (4), and the infrared temperature measurement module (5) is calibrated; then the molybdenum base (2) is installed into the reaction chamber (1), sealed, and then evacuated to a vacuum degree of 1-5 Pa through the vacuum system, and a mixture of methane and hydrogen reaction gas is introduced. Step 2: Coil initialization; Select the layout scheme according to the base size, and set the initial current of each group of coils to 3-3.5A through the multi-channel current control module (4); Step 3: Plasma excitation; Start the microwave source at a frequency of 2.45 GHz to excite the reactive gas to form plasma. Gradually increase the microwave power to 6-8 kW and the gas pressure to around 15 kPa to reach the target temperature for diamond growth. Step 4: Dynamic control of the magnetic field; Open-loop mode: The initial current is continuously maintained or the current is adjusted according to the growth stage based on the preset process parameters; Closed-loop mode: The infrared temperature monitoring module collects the temperature distribution of different points in the radial direction of the diamond in real time. If the temperature difference exceeds 50°C, the multi-channel current control module (4) automatically adjusts the coil current in the corresponding area until the temperature difference is less than or equal to 50°C.

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