A 915 MHz gallium nitride solid-state microwave source for MPCVD diamond growth and a load adaptive control method thereof

Abstract

The application discloses a 915MHz gallium nitride solid-state microwave source for MPCVD diamond growth and a load self-adaptive control method thereof, and belongs to the technical field of microwave energy equipment and semiconductor new material deposition equipment. The microwave source comprises a phase-locked oscillation module, a multi-path GaN power amplification unit, a radial waveguide synthesizer, a bidirectional coupling module, a visual acquisition module and a self-adaptive control module. The multi-path GaN power amplification unit is symmetrically attached to the surface of a micro-channel heat dissipation substrate in a mirror image, the micro-channel cross section is rectangular, the width is 200 microns, and the height is 150 microns; the visual acquisition module collects plasma glow images through a reaction cavity observation window. The self-adaptive control module executes a three-dimensional correction strategy: according to the standing wave ratio, the output frequency is finely adjusted, according to the reflection signal characteristics, a digital pre-distortion lookup table is dynamically adjusted to compensate for amplitude and phase distortion, and an auxiliary magnetic field coil current source is driven to adjust the magnetic field strength.

Description

Technical Field

[0001] This invention belongs to the technical field of microwave energy equipment and semiconductor new material deposition equipment, and in particular relates to a 915MHz gallium nitride solid-state microwave source for MPCVD diamond growth and its load adaptive control method. Background Technology

[0002] Mainstream MPCVD equipment microwave sources mostly use magnetron solutions, which have serious defects such as high-voltage arcing, non-adjustable frequency, average lifespan of less than 5000 hours, severe EMC interference, and inability to dynamically match load in real time, resulting in poor uniformity of large-size diamonds. Existing commercial 915MHz solid-state microwave sources only use a single RF loop adaptive matching: relying solely on forward / reflection power to adjust the frequency or a passive matching network, without direct feedback of the plasma body state; MPCVD process loading has strong time-varying characteristics: methane concentration, chamber temperature, and plasma volume change continuously during the deposition process, and VSWR drifts in real time; radio frequency loop control alone cannot detect the radial uniformity of the plasma, resulting in a diamond film thickness difference of more than 8% and low yield. Current industry bias: Radio frequency matching and plasma uniformity control are two separate systems, and those skilled in the art have no incentive to link and control plasma visual imaging, digital predistortion, and auxiliary magnetic field in a closed loop. Traditional GaN power amplifier arrays use ordinary air-cooled / conventional water-cooled substrates for heat dissipation, which limits power density, causes large temperature differences among multiple GaN devices, results in inconsistent amplification gain, and leads to poor stability of the combined power.

[0003] Therefore, there is an urgent need in this field for a 915MHz GaN solid-state microwave source that can overcome the shortcomings of existing magnetrons and traditional solid-state microwave sources, such as weak load adaptability, poor plasma uniformity, and insufficient heat dissipation consistency of GaN arrays.

[0004] The information disclosed in this background section is intended only to enhance the understanding of the overall background of the invention and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of existing magnetrons and traditional solid-state microwave sources, such as weak load adaptability, poor plasma uniformity, and insufficient heat dissipation consistency of GaN arrays. It provides a 915MHz GaN solid-state microwave source that achieves dynamic load adaptability under all operating conditions through three-dimensional closed-loop control of frequency fine-tuning, digital predistortion (DPD) compensation, and auxiliary magnetic field adjustment, combined with real-time feedback from plasma glow emission vision. This stabilizes the uniformity of large-size single-crystal diamond deposition and improves the long-term reliability of the power amplifier array.

[0006] To achieve the above objectives, the present invention provides the following solution: A 915MHz gallium nitride solid-state microwave source for MPCVD diamond growth includes: Phase-locked oscillator module: configured to output a reference RF signal with a frequency of 915±5MHz, featuring microhertz-level frequency resolution and supporting continuous step frequency modulation.

[0007] Multi-channel GaN power amplifier unit: Several kilowatt-level GaN power devices are mirror-symmetrically mounted on the surface of a microchannel heat dissipation substrate. Each unit receives a reference RF signal and amplifies the power. The microchannel has a rectangular cross-section, 200μm wide × 150μm high. The substrate is made of high thermal conductivity aluminum alloy and is cooled by circulating 25℃ deionized water.

[0008] Radial waveguide synthesizer: configured to synthesize the low-loss power of multiple amplified RF signals into continuous wave microwave energy, and feed it into the MPCVD reaction cavity through the BJ9 standard waveguide interface.

[0009] Bidirectional coupling module: Located in the transmission path, connected in series with the main transmission path, configured to sample forward power Pf and reflected power Pr in real time, and calculate standing wave ratio VSWR in real time.

[0010] Visual acquisition module: configured to acquire plasma glow images through the observation window of the reaction chamber. Specifically, an industrial CMOS camera paired with a hydrogen Balmer narrowband filter is used to acquire plasma glow images through the chamber's observation window.

[0011] Adaptive control module (FPGA hardware architecture): It communicates with the bidirectional coupling module and the vision acquisition module, and communicates with the phase-locked oscillation, bidirectional coupling, vision acquisition and auxiliary magnetic field current source respectively. It has a built-in three-dimensional correction control strategy and is configured to execute the three-dimensional correction strategy.

[0012] Auxiliary magnetic field coil current source: The intensity of the external magnetic field of the cavity is controlled and adjusted to change the electron density distribution inside the cavity.

[0013] Furthermore, the multi-channel GaN power amplifier unit has 16 channels, with a single channel rated output power of 1kW and a total output power of up to 16kW. Each amplifier unit is connected to the coaxial input of the radial waveguide synthesizer via gold wire bonding technology, and the synthesized microwave energy is transmitted to the MPCVD reaction cavity via a BJ9 waveguide.

[0014] The adaptive control module executes a three-dimensional joint correction strategy: Frequency fine-tuning: When the VSWR is greater than the preset threshold, the phase-locked loop frequency fine-tuning is performed first, and the output frequency of the phase-locked oscillation module is fine-tuned. The maximum tuning step size is 3MHz.

[0015] Predistortion compensation: Based on the characteristics of the reflected signal, the amplitude and phase distortion are extracted from the reflected power waveform, and the DPD digital predistortion lookup table is dynamically refreshed to compensate for the nonlinear distortion of the power amplifier.

[0016] Magnetic field fine-tuning: A current source drives the auxiliary magnetic field coils around the reaction chamber, changing the magnetic field strength to adjust the electron density distribution. The vision module processes images to extract the plasma equivalent radius and radial uniformity coefficient (CV); if CV exceeds the process threshold, the magnetic field current source is independently driven to fine-tune the magnetic field.

[0017] Furthermore, the adaptive control module is also configured to perform image processing on the plasma glow image, extract the equivalent radius and radial uniformity coefficient CV of the plasma sphere, and use this coefficient as a weighting factor to dynamically adjust the ratio of the frequency adjustment step size to the magnetic field adjustment step size.

[0018] The system data acquisition cycle is fixed at 1Hz, and the RF power and glow image are continuously adjusted in a closed loop during cyclic sampling.

[0019] A load adaptive control method based on the above-mentioned microwave source includes the following steps: S1: Start the cooling cycle (microchannel water cooling cycle), initialize the phase-locked loop module and GaN power amplifier unit, initialize the phase-locked loop, all GaN power amplifier units, visual acquisition and magnetic field drive module.

[0020] S2: Increase the output power of the microwave source to the target set value, and gradually increase the output power of each GaN power amplifier to the total power set by the process.

[0021] S3: Periodically acquire images of forward power, reflected power, and plasma glow. Forward power Pf, reflected power Pr, and plasma glow images are acquired synchronously every 1 second.

[0022] S4: Based on the joint judgment of VSWR and radial uniformity coefficient, perform at least one of the following operations: frequency fine-tuning, pre-distortion compensation, or magnetic field fine-tuning. VSWR is calculated in real time from Pf and Pr; the plasma radial uniformity coefficient (CV) is extracted through image processing. Correction is performed through a hierarchical judgment using both VSWR and CV indicators. (1) VSWR exceeds the standard and CV synchronization exceeds the standard: prioritize frequency fine-tuning and synchronously update DPD predistortion parameters; (2) VSWR is normal, only CV exceeds the standard: only the auxiliary magnetic field current is finely adjusted to optimize plasma distribution.

[0023] S5: Refresh the control register, repeat steps S3 to S4, continuously collect and correct data until a shutdown command is received.

[0024] S6: Shutdown procedure: power slowly decreases, power supply to the power amplifier drain is turned off, and cooling water circuit is shut down after a delay.

[0025] In a preferred embodiment of the present invention, the microwave source consists of 16 independent GaN power amplifier units, each with a rated output power of 1kW, and a total output power of up to 16kW. The phase-locked loop module employs a low-phase-noise voltage-controlled oscillator, combined with a fractional-frequency phase-locked loop to achieve a stable output at a center frequency of 915MHz. Each amplifier unit is connected to the coaxial input of the radial waveguide synthesizer via gold wire bonding technology, and the synthesized microwave energy is transmitted to the MPCVD reaction cavity via a BJ9 waveguide.

[0026] The microchannel heat dissipation substrate is made of high thermal conductivity aluminum alloy and has parallel flow channels with a rectangular cross-section (200μm wide and 150μm high) processed inside. The cooling medium is deionized water, and the inlet temperature is controlled at 25℃. The vision acquisition module uses an industrial CMOS camera, combined with a narrowband filter to capture the glow region corresponding to the Balmer series spectrum of hydrogen atoms.

[0027] The adaptive control module is implemented based on a field-programmable gate array (FPGA). During diamond deposition, the control module acquires data at a frequency of 1 Hz. When the concentration of methane in the reactant gas increases, causing the plasma volume to expand, the reflected power increases accordingly. At this time, the control module first drives the phase-locked loop module to increase the output frequency by 3 MHz and observes the change in standing wave ratio (VSWR). Subsequently, combined with the plasma edge gradient information extracted by the vision module, the digital predistortion lookup table is fine-tuned to compensate for the amplitude and phase distortion introduced by the frequency shift. Through the above closed-loop adjustment, the radial uniformity coefficient of the plasma sphere is always maintained within 3%, ensuring the uniformity of the diamond film thickness.

[0028] The preferred embodiment has a total power of 16kW, consisting of 16 single-channel 1kW GaN power amplifier units arranged in a mirror image; the microchannel water-cooled substrate controls the temperature difference of all GaN tubes and shells to be less than 3℃.

[0029] Comparative test data: (1) Traditional single frequency modulation solid source: diamond film radial uniformity coefficient CV=8%~12%, VSWR fluctuation range 1.2~2.5; (2) Three-dimensional closed-loop adaptive system of the present invention: CV is stably controlled within 3%, and VSWR ≤1.3 throughout the process cycle; (3) GaN array mirror microchannel heat dissipation scheme: after 2000h continuous aging, the gain difference of each power amplifier is <0.3dB, while the gain difference of the traditional ordinary water-cooled array can reach 1.2dB; (4) No magnetron high voltage circuit, the arcing failure rate of the whole machine is reduced by 95%, and the continuous working life of the equipment is increased by more than 3 times.

[0030] Compared with the prior art, the present invention has the following beneficial effects: By employing GaN solid-state power devices, the high-voltage arcing hazard of magnetrons is eliminated, improving system reliability. The absence of a magnetron-free high-voltage circuit reduces the overall arcing failure rate by 95% and increases the equipment's continuous operating life by more than three times.

[0031] Through three-dimensional closed-loop control involving frequency fine-tuning, pre-distortion compensation, and magnetic field fine-tuning, the system's adaptability to dynamic loads is significantly enhanced. The VSWR over the entire process cycle is ≤1.3, and the radial uniformity coefficient (CV) of the plasma sphere is stably controlled within 3%.

[0032] By introducing a visual feedback mechanism and directly using plasma uniformity as the control target, the deposition quality of large-size diamond films is effectively improved.

[0033] The GaN array solution, which is mounted on a microchannel heat dissipation substrate with mirror symmetry, showed that the gain difference of each power amplifier was less than 0.3dB after 2000 hours of continuous aging, and the array amplitude and phase consistency was significantly better than the traditional solution.

[0034] In addition, the entire hardware structure can be standardized and manufactured. GaN power amplifiers, waveguide synthesis, and FPGA control can all be mass-produced. It is fully compatible with 6-inch MPCVD single crystal diamond production lines. The process indicators can be quantified and stably reproduced, and it has the conditions for large-scale industrialization.

[0035] Unlike existing solid-state sources that only match radio frequency single loops, this invention is the first to couple plasma visual imaging feedback, DPD pre-distortion, and auxiliary magnetic field control into a unified closed-loop control system; it limits the size of the microfluidic channel, the arrangement of the GaN mirror array, and the narrow-band visual acquisition of the hydrogen spectrum, and no existing published literature or patents have the same technical solution.

[0036] The industry has long held a technical bias against the separate design of radio frequency matching and plasma morphology control. Those skilled in the art do not have the technical inspiration to link and combine the three independent control methods. This invention achieves significantly better uniformity and stability indicators than the prior art through multi-dimensional synergistic control, producing unexpected technical effects.

[0037] This invention significantly improves the yield of large-size single-crystal diamonds, reduces equipment maintenance frequency, and eliminates high-voltage safety hazards associated with magnetrons. Attached Figure Description

[0038] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0039] Figure 1 This is a block diagram of the overall structure of the microwave source in an embodiment of the present invention, showing the signal flow and connection relationship between each module.

[0040] Figure 2 This is a schematic diagram of the mirror-symmetric arrangement of the GaN power amplifier unit on the microchannel heat dissipation substrate in an embodiment of the present invention, with the dimensions of the microchannel cross-section marked (width 200μm, height 150μm).

[0041] Figure 3 The flowchart of the load adaptive control method in this embodiment of the invention shows the complete control flow of the VSWR+CV dual-parameter hierarchical correction logic.

[0042] Figure 4 This is a schematic diagram illustrating the principle of plasma glow image processing and feature extraction in an embodiment of the present invention, showing the extraction area and algorithm principle of plasma equivalent radius and radial uniformity coefficient. Detailed Implementation

[0043] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and 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.

[0044] The purpose of this invention is to provide a 915MHz gallium nitride solid-state microwave source for MPCVD diamond growth and its load adaptive control method. Through three-dimensional closed-loop control of frequency fine-tuning, digital predistortion compensation and auxiliary magnetic field adjustment, combined with real-time feedback from plasma glow discharge vision, dynamic load adaptation under all working conditions is achieved, stabilizing the uniformity of large-size single-crystal diamond deposition and improving the long-term reliability of the power amplifier array.

[0045] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0046] Example 1: like Figure 1-4 As shown, in a preferred embodiment of the present invention, the microwave source consists of 16 independent GaN power amplifier units, with a single rated output power of 1kW and a total output power of up to 16kW.

[0047] The phase-locked loop (PLL) module employs a low-phase-noise voltage-controlled oscillator (VCO) in conjunction with a fractional-frequency PLL to achieve a stable output of a 915MHz center frequency, providing microhertz-level frequency resolution and supporting continuous step-modulation. Each amplification unit is connected to the coaxial input of the radial waveguide synthesizer via gold wire bonding technology. The synthesized microwave energy is then transmitted to the MPCVD reaction cavity via a BJ9 waveguide.

[0048] The bidirectional directional coupling module is connected in series with the main transmission path to collect forward power Pf and reflected power Pr in real time and calculate VSWR in real time.

[0049] The microchannel heat dissipation substrate is made of high thermal conductivity aluminum alloy and has parallel flow channels with a rectangular cross-section (200μm wide and 150μm high) processed inside. The cooling medium is deionized water, and the inlet temperature is controlled at 25℃. Multiple kilowatt-level GaN power amplifier devices are mirror-symmetrically mounted on the surface of the microchannel water-cooled substrate.

[0050] The vision acquisition module uses an industrial CMOS camera, with a hydrogen Balmer system narrowband filter set at the front of the camera lens. It captures the glow region corresponding to the hydrogen atom Balmer system spectrum through the cavity observation window and acquires plasma glow images.

[0051] The adaptive control module is implemented based on a field-programmable gate array (FPGA) and communicates with the phase-locked oscillation module, the bidirectional coupling module, the vision acquisition module, and the auxiliary magnetic field current source, respectively. It has a built-in three-dimensional correction control strategy.

[0052] The auxiliary magnetic field coil current source is controlled to adjust the strength of the external magnetic field of the cavity, thereby changing the electron density distribution inside the cavity.

[0053] During diamond deposition, the control module synchronously acquires forward power (Pf), reflected power (Pr), and plasma glow images at a frequency of 1 Hz. The standing wave ratio (VSWR) is calculated in real-time from Pf and Pr, and the radial uniformity coefficient (CV) of the plasma is extracted through image processing. When the concentration of methane in the reactant gas increases, causing plasma volume expansion, the reflected power rises accordingly. At this point, the control module first drives the phase-locked loop module to increase the output frequency by 3 MHz and observes the change in VSWR. Subsequently, combined with the plasma edge gradient information extracted by the vision module, the digital predistortion lookup table is fine-tuned to compensate for the amplitude and phase distortion introduced by the frequency shift. Through this closed-loop adjustment, the radial uniformity coefficient of the plasma sphere is consistently maintained within 3%, ensuring the uniformity of the diamond film thickness.

[0054] The specific process of the control method is as follows: S1: Start the microchannel water cooling cycle, and initialize the phase-locked loop, all GaN power amplifier units, and the visual acquisition and magnetic field drive module.

[0055] S2: Stepwise increase the output power of each GaN power amplifier to the total power set by the process.

[0056] S3: Synchronously acquire positive power Pf, reflected power Pr, and plasma glow images every 1 second.

[0057] S4: VSWR is calculated in real time from Pf and Pr; the radial homogeneity coefficient CV of the plasma is extracted by image processing.

[0058] S5: Combined VSWR and CV dual-indicator hierarchical judgment and correction: (1) VSWR exceeds the standard and CV synchronization exceeds the standard: prioritize frequency fine-tuning and synchronously update DPD predistortion parameters; (2) VSWR is normal, only CV exceeds the standard: only the auxiliary magnetic field current is finely adjusted to optimize plasma distribution; (3) VSWR normal, CV normal: maintain the current parameters.

[0059] S6: Refresh the control register and continuously collect and correct data until a shutdown command is received.

[0060] S7: Shutdown procedure: power slowly decreases, power supply to the power amplifier drain is turned off, and cooling water circuit is shut down after a delay.

[0061] In the preferred embodiment, the microfluidic water-cooled substrate controls the temperature difference of all GaN tubes to be less than 3°C. Comparative test data shows that the radial uniformity coefficient (CV) of the diamond film in a traditional single-frequency tuned solid-state source is 8%~12%, and the VSWR fluctuates between 1.2 and 2.5; while the CV of the three-dimensional closed-loop adaptive system of this invention is stably controlled within 3%, and the VSWR is ≤1.3 throughout the entire process cycle. After 2000 hours of continuous aging, the gain difference of each power amplifier in the GaN array mirror microfluidic heat dissipation scheme is less than 0.3dB, while the gain difference of a traditional ordinary water-cooled array can reach 1.2dB. In addition, due to the absence of a magnetron high-voltage circuit, the overall arcing failure rate is reduced by 95%, and the continuous working life of the equipment is increased by more than 3 times.

[0062] Example 2: The difference between this embodiment and Embodiment 1 lies in that the adaptive control module is configured to perform image processing on the plasma glow image, extract the equivalent radius and radial uniformity coefficient (CV) of the plasma sphere, and use this coefficient as a weighting factor to dynamically adjust the ratio of the frequency adjustment step size to the magnetic field adjustment step size. Specifically, when the CV value is large (indicating uneven plasma distribution), the ratio of the magnetic field adjustment step size to the frequency adjustment step size is increased, prioritizing the improvement of plasma distribution uniformity through magnetic field adjustment; when the CV value is small, the default adjustment ratio is maintained. By introducing CV as a weighting factor, optimized allocation of control resources is achieved, further improving the system's adaptive capability and adjustment efficiency.

[0063] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the systems disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the descriptions are relatively simple; relevant parts can be referred to the method section.

[0064] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. Furthermore, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A 915MHz gallium nitride solid-state microwave source for MPCVD diamond growth, characterized in that, include: The phase-locked oscillator module is configured to output a reference RF signal with a frequency of 915±5MHz and has a microhertz-level frequency resolution. A multi-channel GaN power amplifier unit, each receiving the reference RF signal and amplifying it, is mounted mirror-symmetrically on the surface of a microchannel heat dissipation substrate. The microchannel inside the microchannel heat dissipation substrate has a rectangular cross-section with a width of 200μm and a height of 150μm. A radial waveguide synthesizer is configured to synthesize multi-amplified radio frequency signals into continuous wave microwave energy and feed it into the MPCVD reaction cavity through a BJ9 standard waveguide interface. A bidirectional coupling module is placed in the transmission path and configured to sample forward power and reflected power in real time; The visual acquisition module is configured to acquire plasma glow images through the observation window of the reaction chamber; An adaptive control module is communicatively connected to the phase-locked oscillation module, the bidirectional coupling module, and the vision acquisition module, and is configured to execute a three-dimensional correction strategy. The three-dimensional correction strategy includes: fine-tuning the output frequency of the phase-locked oscillation module according to the standing wave ratio, dynamically adjusting the digital predistortion lookup table according to the characteristics of the reflected signal to compensate for amplitude and phase distortion, and driving the current source of the auxiliary magnetic field coil around the reaction cavity to adjust the magnetic field strength.

2. The 915MHz gallium nitride solid-state microwave source for MPCVD diamond growth according to claim 1, characterized in that, The vision acquisition module includes an industrial CMOS camera and a hydrogen Balmer narrowband filter. The narrowband filter is disposed at the front end of the lens of the industrial CMOS camera and is used to selectively transmit the glow signal corresponding to the hydrogen atom Balmer spectrum.

3. The 915MHz gallium nitride solid-state microwave source for MPCVD diamond growth according to claim 1, characterized in that, The microchannel heat dissipation substrate is made of high thermal conductivity aluminum alloy, and 25°C deionized water is circulated into the microchannel as a circulating cooling medium.

4. The 915MHz gallium nitride solid-state microwave source for MPCVD diamond growth according to claim 1, characterized in that, The adaptive control module is based on an FPGA hardware architecture. In the three-dimensional correction strategy, when the standing wave ratio is greater than the preset threshold, frequency fine-tuning is performed first, and the maximum single tuning step size is 3MHz.

5. The 915MHz gallium nitride solid-state microwave source for MPCVD diamond growth according to claim 1, characterized in that, The adaptive control module is further configured to perform image processing on the plasma glow image, extract the radial uniformity coefficient of the plasma, and use the radial uniformity coefficient as a weighting factor to dynamically adjust the ratio of the frequency adjustment step size to the magnetic field adjustment step size.

6. The 915MHz gallium nitride solid-state microwave source for MPCVD diamond growth according to claim 1, characterized in that, The multi-channel GaN power amplifier unit has 16 channels, with a single channel rated output power of 1kW and a combined power of not less than 16kW.

7. The 915MHz gallium nitride solid-state microwave source for MPCVD diamond growth according to claim 1, characterized in that, The adaptive control module has a data acquisition cycle of 1Hz, cyclically acquiring forward power, reflected power, and plasma glow images, and continuously adjusting them in a closed loop.

8. A load adaptive control method for a 915MHz gallium nitride solid-state microwave source for MPCVD diamond growth according to any one of claims 1 to 7, characterized in that, Includes the following steps: S1: Start the cooling cycle and initialize the phase-locked loop module and GaN power amplifier unit; S2: Increase the output power of the microwave source to the target set value; S3: Periodically acquire images of forward power, reflected power, and plasma glow. S4: Based on the joint judgment result of the standing wave ratio and the plasma radial uniformity coefficient, perform at least one of the following operations: frequency fine-tuning, digital predistortion compensation, or magnetic field fine-tuning. S5: Repeat steps S3 to S4 until a shutdown command is received.

9. The load adaptive control method according to claim 8, characterized in that, In step S4, when the standing wave ratio is greater than the preset threshold and the radial uniformity coefficient is greater than the preset threshold, frequency fine-tuning is performed first and digital predistortion parameters are updated synchronously; when the standing wave ratio is less than or equal to the preset threshold and the radial uniformity coefficient is greater than the preset threshold, only the auxiliary magnetic field current is fine-tuned to optimize the plasma distribution.

10. The load adaptive control method according to claim 8, characterized in that, When the shutdown command is executed, the power is gradually reduced, the power supply to the power amplifier drain is turned off, and the cooling water circuit is shut down after a delay.

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