Microwave ion source self-adaptive control method and system based on output current

Abstract

The application discloses a microwave ion source adaptive control method and system with output current as the core, and the system of the microwave ion source adaptive stable control with the output current as the core comprises a parameter monitoring module, a matching network module, a microwave power control module and an intelligent decision controller, the intelligent decision controller is configured to execute the microwave ion source adaptive control method with the output current as the core. The application overturns the traditional "minimum reflection power priority" control paradigm, establishes the core principle of "screen-grid current standard priority, safe constraint of reflection power", through the hierarchical and dead-zone intelligent coordination logic, the target is clear, unnecessary actions are effectively reduced, the stability of system operation is improved, the coupling and oscillation of the control loop are reduced, and the system is ensured to quickly and stably reach and maintain the set process target.

Description

Technical Field

[0001] This invention relates to an adaptive control method and system for microwave ion sources with output current as the core. Background Technology

[0002] Microwave ion sources are widely used in ion implantation, thin film deposition, and other fields. Their core performance indicators are the ability to stably output set values ​​of grid voltage and current, with the grid current directly determining the process beam current intensity. Microwave ion source systems maintain stable operation through the following adjustable parameters: 1. Microwave matching network: used to adjust impedance matching, minimize reflected power, and ensure efficient transmission of microwave energy to plasma.

[0003] 2. Microwave source power: directly determines the amount of energy input into the ionization chamber.

[0004] 3. Other parameters: such as gas flow rate, magnetic field strength, etc.

[0005] Current mainstream control strategies typically follow the principle of "minimizing reflected power first," meaning the control system continuously adjusts the matching network to minimize reflected power, which is considered a necessary prerequisite for achieving high grid current and stable operation. However, this strategy has significant drawbacks in real-world complex operating conditions: 1. Target Misalignment: Reflected power is an intermediate process parameter, while grid current is the final process result. Since the optimal matching point (minimum reflected power) does not always correspond to the maximum or stable point of the grid current, the system converges to a "high-efficiency, low-energy" state that is ineffective for the process.

[0006] 2. Over-adjustment and instability: When the grid current has reached the process requirements, if the matching network is adjusted again simply because the reflected power has not reached the theoretical minimum value, it will destroy the established stable plasma state, cause current fluctuations, and even lead to flameout.

[0007] 3. Control loop coupling and oscillation: Microwave power regulation and matching network regulation are both strongly coupled loops. If there is no clear priority and coordination logic between the two, they are prone to mutual interference, causing the system to oscillate repeatedly around the target value and become unstable. Summary of the Invention

[0008] The purpose of this invention is to provide an adaptive control method for microwave ion sources with output current as the core, in order to solve the problems of target misalignment, over-adjustment and instability, control loop coupling and oscillation that are easily caused by the mainstream control strategy based on the principle of "minimizing reflected power".

[0009] This invention is achieved through the following technical solution: The adaptive control method for microwave ion sources, with output current as the core, comprises the following steps: S1: Obtain the screen grid current \(I_{screen}\). S2: When \(I_{match}<|\Delta I|<I_{power}\), trigger the automatic adjustment process of the matching network. Where \(|\Delta I| = |I_{screen}-I_{set}|\), \(I_{set}\) is the target screen grid current, \(I_{match}\) is the narrow current dead zone value, \(I_{power}\) is the wide current dead zone value, and \(I_{power}>I_{match}\). S3: Enter the automatic adjustment process of the matching network, and the steps are as follows: S31: The pin moves under control. S32: Obtain the reflected power \(P_{refl}\) and the screen grid current \(I_{screen}\) in real time. S33: If \(|\Delta I|<I_{match}\) and \(P_{refl}<P_{safe}\), terminate the automatic adjustment process of the matching network, and the pin is locked at the current position. If \(|\Delta I|<I_{match}\) but \(P_{refl}>P_{safe}\) or \(I_{match}<|\Delta I|<I_{power}\), then repeat steps S31 - S33. If \(|\Delta I|>I_{power}\), then trigger the microwave power adjustment process. Where \(P_{safe}\) is the reflected power safety value. S4: Enter the microwave power adjustment process, and the steps are as follows: S41: Increase or decrease the microwave power. S42: Obtain the reflected power \(P_{refl}\) and the screen grid current \(I_{screen}\). S43: If \(|\Delta I|<I_{match}\) and \(P_{refl}<P_{safe}\), then the microwave power adjustment process ends. If \(I_{match}<|\Delta I|<I_{power}\), then trigger the automatic adjustment process of the matching network, and repeat steps S31 - S33. If \(|\Delta I|>I_{power}\), then repeat steps S41 - S43.

[0010] Further, in step S33, if \(|\Delta I|\) is greater than \(I_{power}\) for \(T1\) seconds continuously, then trigger the microwave power adjustment process.

[0011] The value range of \(T1\) is: 1 - 3 seconds.

[0012] Further, in step S41: If \(I_{screen}<(I_{set}-I_{power})\), then increase the microwave power. If I_screen > (I_set + I_power), then reduce the microwave power.

[0013] Furthermore, in step S41: If I_screen lasts for T2 seconds and is less than (I_set - I_power), then increase the microwave power; If I_screen lasts for T3 seconds and is greater than (I_set + I_power), then reduce the microwave power.

[0014] Furthermore, the value range of T2 is 1 to 3 seconds, and the value range of T3 is 1 to 3 seconds.

[0015] Furthermore, the value range of I_match is 2 to 4 mA, and the value range of I_power is 9 to 11 mA.

[0016] To address the problems of target misalignment, over-adjustment and instability, and control loop coupling and oscillation that arise from the mainstream control strategy's "minimize reflected power" principle, this invention provides an adaptive control method for microwave ion sources based on output current. Correspondingly, it also provides a system for adaptive and stable control of microwave ion sources based on output current, comprising: Parameter monitoring module: used to collect screen current I_screen and reflected power P_refl in real time; Matching network module: includes pins and a motor, the pins being moved by the motor; Microwave power control module: used to set and adjust the output power of the microwave source; Intelligent decision controller: It is configured to execute the above-mentioned microwave ion source adaptive control method with output current as the core.

[0017] The advantages of this technical solution are: 1. Process Goal Orientation: The core of control is completely transformed from intermediate variables (reflection power) to the final process index (grid current), ensuring that the control behavior always serves the actual application needs.

[0018] 2. Significantly improved operational stability: By introducing a dual dead zone (I_match, I_power) and the rule of "stopping when current reaches the target", the over-adjustment and system oscillation caused by pursuing the theoretical optimum (minimum reflection) are fundamentally eliminated, enabling the ion source to operate stably at the set point for a long time.

[0019] 3. Intelligent Coordination and Protection: The primary and secondary relationships and trigger thresholds of matching regulation and power regulation are clearly defined, avoiding conflicts between control loops. Simultaneously, the P_safe setting provides necessary safety boundaries when pursuing current targets.

[0020] 4. Reduce unnecessary actions: Significantly reduce the action frequency of the matching network and the microwave power source, reduce mechanical wear and device fatigue, and improve the overall reliability of the system.

[0021] 5. Strong adaptability: It can cope with slow-changing disturbances caused by process gas changes, grid contamination, magnetic field drift, etc., and automatically stabilize the output current near the target value through two-layer coordinated control. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings required for description in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for description in the embodiments.

[0024] Figure 1 FIG. 15 is a flowchart of the adaptive control method for a microwave ion source with output current as the core in Embodiment 1 of the present invention; Figure 2 FIG. 18 is a schematic structural diagram of the adaptive control method for a microwave ion source with output current as the core in Embodiment 2 of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0025] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0026] Embodiment 1: As Figure 1 shown, the adaptive control method for a microwave ion source with output current as the core is as follows: S_{1}: Obtain the screen grid current I_{screen}; S_{2}: When I_{match}<|ΔI|<I_{power}, trigger the automatic adjustment process of the matching network; where |ΔI| = |I_{screen}-I_{set}|, I_{set} is the target screen grid current, I_{match} is the narrow current dead zone value, I_{power} is the wide current dead zone value, and I_{power}>I_{match}; S_{3}: Enter the automatic adjustment process of the matching network, and the steps are as follows: S_{31}: The pin is controlled to move; S32: Obtain the reflection power P_refl and the screen grid current I_screen in real time; S33: If |ΔI| < I_match and P_refl < P_safe, terminate the automatic adjustment process of the matching network, and lock the pin at the current position; If |ΔI| < I_match but P_refl > P_safe or I_match < |ΔI| < I_power, then repeat steps S31 - S33; If |ΔI| > I_power, then trigger the microwave power adjustment process; Among them, P_safe is the safe value of the reflection power; S4: Enter the microwave power adjustment process, and the steps are as follows: S41: Increase or decrease the microwave power; S42: Obtain the reflection power P_refl and the screen grid current I_screen; S43: If |ΔI| < I_match and P_refl < P_safe, then the microwave power adjustment process ends; If I_match < |ΔI| < I_power, then trigger the automatic adjustment process of the matching network, and repeat steps S31 - S33; If |ΔI| > I_power, then repeat steps S41 - S43.

[0027] Among them, I_set, I_match, and I_power are all preset values.

[0028] This embodiment provides a microwave ion source adaptive control method with the output current as the core to solve the problems of target misalignment, over - adjustment and instability, and control loop coupling and oscillation easily caused by the mainstream control strategy based on the principle of "minimizing reflection power first". It mainly continuously compares I_screen with I_set, I_match, and I_power, and according to the comparison results, enables the adjustment of the matching network or the microwave power. During the adjustment process of the matching network, it compares P_refl with P_safe in real time, and jointly decides the adjustment termination point with the current compliance status, manages the timing of the two adjustment levels, and avoids conflicts. This invention subverts the traditional "minimizing reflection power first" control paradigm, establishes the core principle of "screen grid current compliance first, reflection power safety constraint", and through hierarchical and dead - zone intelligent coordination logic, has a clear target orientation, effectively reduces unnecessary actions, improves the stability of system operation, reduces control loop coupling and oscillation, and ensures that the system quickly and smoothly reaches and maintains the set process target.

[0029] The advantages are as follows: 1. Process Goal Orientation: The core of control is completely transformed from intermediate variables (reflection power) to the final process index (grid current), ensuring that the control behavior always serves the actual application needs.

[0030] 2. Significantly improved operational stability: By introducing a dual dead zone (I_match, I_power) and the rule of "stopping when current reaches the target", the over-adjustment and system oscillation caused by pursuing the theoretical optimum (minimum reflection) are fundamentally eliminated, enabling the ion source to operate stably at the set point for a long time.

[0031] 3. Intelligent Coordination and Protection: The primary and secondary relationships and trigger thresholds of matching regulation and power regulation are clearly defined, avoiding conflicts between control loops. Simultaneously, the P_safe setting provides necessary safety boundaries when pursuing current targets.

[0032] 4. Reduce unnecessary actions: Significantly reduce the operating frequency of the matching network and microwave power source, reduce mechanical wear and device fatigue, and improve the overall reliability of the system.

[0033] 5. Strong adaptability: It can cope with slow-changing interference caused by process gas changes, grid contamination, magnetic field drift, etc., and automatically stabilize the output current near the target value through two-layer coordinated control.

[0034] In this embodiment of the invention, in step S33, if |ΔI| is greater than I_power for T1 seconds, then the microwave power adjustment process is triggered.

[0035] In this embodiment of the invention, the value range of T1 is 1 to 3 seconds.

[0036] In this embodiment of the invention, in step S41: If I_screen < (I_set - I_power), then increase the microwave power; If I_screen > (I_set + I_power), then reduce the microwave power.

[0037] In this embodiment of the invention, in step S41: If I_screen lasts for T2 seconds and is less than (I_set - I_power), then increase the microwave power; If I_screen lasts for T3 seconds and is greater than (I_set + I_power), then reduce the microwave power.

[0038] In this embodiment of the invention, the value range of T2 is 1 to 3 seconds, and the value range of T3 is 1 to 3 seconds.

[0039] In this embodiment of the invention, the value range of I_match is 2 to 4 mA, and the value range of I_power is 9 to 11 mA.

[0040] Example 2: As Figure 2 As shown, this microwave ion source adaptive stabilization control system, with output current as its core, includes: Parameter monitoring module 1: used to collect screen current I_screen and reflected power P_refl in real time; Matching network module 2: includes pin 201 and motor 202, pin 201 is driven to move by motor 202; Microwave power control module 3: Used to set and adjust the output power of the microwave source; Intelligent decision controller 4: It is configured to execute the above-mentioned microwave ion source adaptive control method with output current as the core.

[0041] It should be understood that the terms "first," "second," etc., are used in this invention to describe various information, but this information should not be limited to these terms. These terms are only used to distinguish information of the same type from each other. For example, without departing from the scope of this invention, "first" information can also be referred to as "second" information, and similarly, "second" information can also be referred to as "first" information. In addition, the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this invention and 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, and therefore should not be construed as a limitation of this invention.

[0042] The above description provides one or more embodiments in conjunction with specific content, and does not imply that the specific implementation of the present invention is limited to these descriptions. Any methods or structures similar to or identical to those of the present invention, or any technical deductions or substitutions made based on the concept of the present invention, should be considered as protected by the present invention.

Claims

1. An adaptive control method for a microwave ion source based on output current, characterized in that, The steps are as follows: S1: Obtain the screen grid current I_screen; S2: When I_match < |ΔI| < I_power, trigger the automatic adjustment process of the matching network; where, |ΔI| = |I_screen - I_set|, I_set is the target screen grid current, I_match is the narrow current dead zone value, I_power is the wide current dead zone value, and I_power > I_match; S3: Enter the automatic adjustment process of the matching network, and the steps are as follows: S31: The pin is controlled to move; S32: Obtain the reflected power P_refl and the screen grid current I_screen in real time; S33: If |ΔI| < I_match and P_refl < P_safe, terminate the automatic adjustment process of the matching network, and the pin is locked at the current position; If |ΔI| < I_match but P_refl > P_safe or I_match < |ΔI| < I_power, then repeat steps S31 - S33; If |ΔI| > I_power, then trigger the microwave power adjustment process; where, P_safe is the reflected power safety value; S4: Enter the microwave power adjustment process, and the steps are as follows: S41: Increase or decrease the microwave power; S42: Obtain the reflected power P_refl and the screen grid current I_screen; S43: If |ΔI| < I_match and P_refl < P_safe, then the microwave power adjustment process ends; If I_match < |ΔI| < I_power, then trigger the automatic adjustment process of the matching network and repeat steps S31 - S33; 2. The microwave ion source adaptive control method based on output current as described in claim 1, characterized in that, If |ΔI| > I_power, then repeat steps S41 - S43.

3. The adaptive control method for a microwave ion source based on output current as described in claim 2, characterized in that, In step S33, if |ΔI| is greater than I_power for T1 seconds continuously, then trigger the microwave power adjustment process.

4. The adaptive control method for a microwave ion source based on output current as described in claim 1, characterized in that, The value range of T1 is: 1 - 3 seconds. In step S41: If I_screen < (I_set - I_power), then increase the microwave power; 5. The microwave ion source adaptive control method based on output current as described in claim 4, characterized in that, If I_screen > (I_set + I_power), then decrease the microwave power. In step S41: If I_screen is less than (I_set - I_power) for T2 seconds continuously, then increase the microwave power; 6. The adaptive control method for a microwave ion source based on output current as described in claim 5, characterized in that, If I_screen is greater than (I_set + I_power) for T3 seconds continuously, then decrease the microwave power.

7. The adaptive control method for a microwave ion source based on output current as described in claim 1, characterized in that, The value range of T2 is: 1 - 3 seconds, and the value range of T3 is: 1 - 3 seconds.

8. A microwave ion source adaptive stabilization control system with output current as the core, characterized in that, The value range of I_match is: 2 - 4 mA, and the value range of I_power is: 9 - 11 mA. It includes: Parameter monitoring module: used to collect the screen grid current I_screen and the reflected power P_refl in real time; Matching network module: includes a pin and a motor, and the pin is driven by the motor to move; Microwave power control module: used to set and adjust the output power of the microwave source; Intelligent decision controller: configured to execute the microwave ion source adaptive control method with the output current as the core described in any one of claims 1 - 7.

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