Radio frequency power supply system and modulation power overshoot prevention method

Abstract

The invention provides a radio frequency power supply system and a modulation power overshoot prevention method, the method relates to a low-frequency high-power radio frequency power supply system, and the system core comprises a radio frequency signal driving module, a power amplifier module, a power synthesis module, a power detection module and a processor module. In the power climbing stage of converting low power into high power, when the power is required to be quickly increased, the phenomenon of output power overshoot exists. In the power climbing stage, the phase difference of the two paths of radio frequency driving signals is adjusted and the power supply voltage of the power amplifier is reduced through a nonlinear method, so that power overshoot is effectively suppressed, and stable operation of the radio frequency power supply is ensured.

Description

Technical Field

[0001] The present invention relates to the technical field of radio frequency power supply, in particular to a radio frequency power supply system and a modulation method for preventing power overshoot. Background Art

[0002] RF power supplies play a vital role in many fields, such as in the semiconductor device manufacturing process, especially in key process steps such as etching, ion implantation, and thin film deposition. The stability and accuracy of RF power pulse power output directly affect the performance and yield of semiconductor devices. The stability of pulse power output not only requires that the output power can respond quickly to changes in the control signal, but also ensures that there will be no overshoot or undershoot during the power ramp-up and ramp-down process, so as to avoid unnecessary damage to semiconductor materials or affect the consistency and repeatability of the process.

[0003] However, in practical applications, RF power systems often encounter the following problems when facing rapidly changing pulse power requirements: Figure 3 The power overshoot problem is shown in the figure. This is mainly due to the limited response speed and control accuracy of the power amplifier when the system quickly switches from a low power state to a high power state during the power ramp-up phase, causing the output power to exceed the set value in a short period of time. Power overshoot not only causes the performance of semiconductor devices to deteriorate, but may also cause equipment failure, increase production costs and process complexity.

[0004] The patent with document number CN110504149 A mentions a pulse modulation system for an RF power supply, the core of which is to use the frequency adjustment module and the sweep matching algorithm to automatically adjust the RF frequency of the pulse modulated RF signal in the overshoot sub-stage, so that the reflected power or reflection coefficient in the overshoot sub-stage meets the requirements. This method is to calculate the real-time power-related parameters of each frequency point by sweeping the frequency, and then take the frequency when the reflection coefficient is the smallest. A large amount of calculation is required during the sweeping period, and it is inevitable that it will take a certain amount of time to obtain the optimal frequency. And when the RF power supply is required to work in a fixed frequency mode with poor load matching, this method needs to be re-optimized.

[0005] Therefore, how to effectively improve the stability of the RF power supply pulse power output without increasing the system complexity and cost, especially to prevent power overshoot during the power ramp-up phase, has become a key technology that has been concerned about in the current RF power supply technology field. Summary of the invention

[0006] 1. Technical issues to be solved

[0007] In view of the deficiencies in the prior art, the present invention provides a radio frequency power supply system and a method for modulating power overshoot prevention, which solves the problem of how to effectively improve the stability of the pulse power output of the radio frequency power supply without increasing the complexity and cost of the system.

[0008] (II) Technical solution

[0009] The purpose of the present invention is to overcome the shortcomings of the existing pulse modulation method and propose a radio frequency power supply system and a modulation method for preventing power overshoot. The method effectively suppresses power overshoot in the power climbing stage by nonlinearly adjusting the phase difference of two radio frequency drive signals and reducing the power supply voltage of the power amplifier, thereby ensuring the stable operation of the radio frequency power supply.

[0010] The technical solution of the present invention is: a radio frequency power supply system, including a radio frequency signal driving module, a power amplifier module, a power synthesis module, a power detection module and a processor module;

[0011] RF signal driving module: used to output two phase-adjustable RF driving signals, each signal driving a group of power amplifiers;

[0012] Power amplifier module: connected to the RF signal driving module, responsible for amplifying the driving signal to the required power level. This module contains two power amplifier modules and can adjust the power supply voltage of the power amplifier module;

[0013] Power synthesis module: connected to the two power amplifier modules of the RF power amplifier, effectively superimposing the power output of the two power amplifier modules to form the final RF pulse power output.

[0014] Power detection module: used to detect output power and feed back the voltage and current signals of the real-time detected output power to the processor module.

[0015] Processor module: used to receive external instructions and voltage and current signals fed back by the power detection module, and automatically adjust the phase difference of the two drive signals of the RF signal drive module and the supply voltage of the power amplifier module according to the set pulse frequency and power requirements to achieve precise control of the output power.

[0016] As a preferred embodiment of the present invention, the transmission of the RF signal in the RF signal driving module adopts a differential method, and a digital-to-analog conversion chip is used in the RF signal driving module. The digital-to-analog conversion chip has two independent digital-to-analog conversion channels and can process two RF signals simultaneously.

[0017] As a preferred embodiment of the present invention, a water tray high heat dissipation component is used in the power amplifier module. As a preferred embodiment of the present invention, a method for preventing power overshoot by pulse modulation of a radio frequency power supply specifically comprises the following: a radio frequency power supply system monitors the high power and low power states of the pulse power output in real time;

[0018] When low power is converted to high power, the system completes 80% phase difference adjustment of the two RF drive signals in the first 40% of the power ramp-up phase;

[0019] When low power is converted to high power, the system completes the remaining 20% ​​phase difference adjustment within 60% of the time after the power ramp-up phase;

[0020] During the power ramp-up phase, the power amplifier module supply voltage is modulated to 90% of the high-power voltage;

[0021] When the phase difference adjustment of the two RF driving signals is completed, the supply voltage of the power amplifier module will be modulated to 100% of the voltage at high power.

[0022] As a preferred embodiment of the present invention, the pulse cycle frequency range of the pulse modulated RF signal is 100HZ-10KHZ, and in each pulse cycle, the RF power supply system outputs high power when the pulse is at a high level and outputs low power when the pulse is at a low level.

[0023] As a preferred embodiment of the present invention, the power ramp-up phase time is also less than 15 us.

[0024] As a preferred embodiment of the present invention, it also includes that during pulse power modulation, the phase difference adjustment process of the two RF drive signals in the power ramp-up stage is nonlinear.

[0025] (III) Beneficial effects

[0026] The present invention provides a radio frequency power supply system and a method for modulating power overshoot prevention, which has the following beneficial effects:

[0027] Effectively suppress power overshoot: By nonlinearly adjusting the phase difference between two RF drive signals and reducing the power amplifier supply voltage, the present invention effectively suppresses the power overshoot phenomenon during the power ramp-up phase.

[0028] Improve system stability: The control method of the present invention ensures the stable operation of the RF power supply system during the pulse power modulation process, and avoids damage to system equipment caused by power overshoot.

[0029] Flexible and adjustable: The RF power supply system of the present invention allows the supply voltage of the power amplifier module to be adjusted, and the phase difference adjustment process is nonlinear, so that the system can be flexibly adjusted according to the needs of different application scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic diagram of the core framework of the radio frequency power supply system of the present invention;

[0031] Figure 2 This is the ideal pulse power output waveform;

[0032] Figure 3 Schematic diagram of pulse power output for overshoot

[0033] Figure 4 This is the pulse power output waveform of overshoot

[0034] Figure 5 Schematic diagram of power increase when switching from low power to high power

[0035] Figure 6 The present invention is a schematic diagram of the working process of the method. DETAILED DESCRIPTION

[0036] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] See also Figure 1-6 An embodiment of the present invention provides a technical solution: a method for preventing power overshoot by pulse modulation of an RF power supply. The RF power supply system includes an RF signal driving module, a power amplifier module, a power synthesis module, a power detection module and a processor module.

[0038] The RF signal driver module is used to output two phase-adjustable RF drive signals, each of which drives a group of power amplifiers. The RF signal in the RF signal driver module is transmitted in a differential manner. Differential transmission can effectively offset external electromagnetic interference and ensure the stability and reliability of the RF signal during transmission.

[0039] The digital-to-analog conversion chip used in the RF signal driving module has two independent digital-to-analog conversion channels and can process two RF signals simultaneously.

[0040] The digital-to-analog conversion chip used in the RF signal driving module has high sampling rate, high signal-to-noise ratio and good linearity.

[0041] The RF power amplifier module is connected to the RF signal driver module and is responsible for amplifying the drive signal to the required power level. The RF power amplifier module has two power amplifier modules. In order to output high power, the system allows the power supply voltage of the power amplifier module to be adjusted. The power amplifier module needs to have high output power and good linearity to ensure signal transmission and reduce distortion. At the same time, high efficiency and stability are also required to reduce energy consumption and ensure long-term reliable operation of the system. The power amplifier module needs to be equipped with a water pan high heat dissipation component to ensure stable high power output.

[0042] The power synthesis module is connected to the two power amplifier modules of the RF power amplifier, and effectively superimposes the power output of the two power amplifier modules to form the final RF pulse power output.

[0043] The power detection module is responsible for detecting the output power, detecting the voltage and current signals of the output power in real time and feeding them back to the processor module.

[0044] The processor module is mainly responsible for receiving external instructions and the voltage and current signals fed back by the power detection module. According to the set pulse frequency and power requirements, it automatically adjusts the phase difference of the two drive signals of the RF signal drive module and the supply voltage of the power amplifier module to achieve precise control of the output power.

[0045] The pulse cycle frequency range of the pulse modulated RF signal is 100HZ-10KHZ. In each pulse cycle, the RF power supply system outputs high power when the pulse is at a high level and outputs low power when the pulse is at a low level.

[0046] In both high-power and low-power output states, there is a specific phase difference between the two RF drive signals. At high power, the phases of the two RF drive signals are close, and at low power, the phase difference between the two RF drive signals is large.

[0047] When low power is converted to high power, there is a transition period, which is called the power ramp-up phase. The power ramp-up phase is extremely short, less than 15us.

[0048] During pulse power modulation, the phase difference adjustment process of the two RF drive signals during the power ramp-up phase is not linear.

[0049] A method for preventing power overshoot by pulse modulation of radio frequency power supply comprises the following steps:

[0050] Real-time monitoring: The RF power system monitors the high power and low power states during pulse power output in real time.

[0051] Phase difference adjustment 1: When low power is converted to high power, the system completes 80% phase difference adjustment of the two RF drive signals in the first 40% of the power ramp-up phase;

[0052] Phase difference adjustment 2: When low power is converted to high power, the system completes the remaining 20% ​​phase difference adjustment within 60% of the power ramp-up phase. This nonlinear adjustment method ensures that the phase difference is rapidly approached during most of the power ramp-up phase, and when there is only 20% left, it starts to adjust slowly to achieve a smooth power transition.

[0053] Supply voltage modulation: During the power ramp-up phase, the supply voltage of the power amplifier module will be modulated to 90% of the voltage at high power; when the phase difference adjustment of the two RF drive signals is completed, the supply voltage of the power amplifier module will be modulated to 100% of the voltage at high power.

[0054] Embodiment 1

[0055] S1: Start working, turn on the power, and go to the next step after the power indicator light is normal;

[0056] S2: Check whether the safety lock is normal. The safety lock is a linkage protection mechanism to determine whether the RF power supply is connected to the load. It is connected in series in the protection circuit and used as a protection switch.

[0057] S3: Determine whether the pulse power parameter setting command is received: After the system is powered on normally, the processor module receives the host computer command through the communication interface, mainly the serial port or the network port, and completes the setting of the relevant parameters related to the pulse power output, such as frequency, high power, low power, duty cycle, pulse period, etc.

[0058] S4: Determine whether to start power output: After the system power-related parameter commands are set, wait for the RF start command. Once the start command is received, enter the next step of power output modulation. If no power output command is received, it is in a waiting state;

[0059] S5: Pulse power modulation mode: After entering the pulse power modulation mode, the RF system will set the preset voltage and power corresponding to the phase difference, output the initial voltage and two RF drive signals;

[0060] S6: Power detection: The RF power system detects the voltage and current signals of the output power in real time through the power detection module. The processor module FPGA extracts the amplitude and phase information of the feedback signal voltage and current through digital filtering and demodulation based on the feedback voltage and current signals. The FPGA processor has a DSP core inside, which can be used to quickly calculate floating-point numbers and quickly calculate the actual output power of the RF power supply based on the amplitude and phase information. Some of the formulas are as follows:

[0061] Load power: Pload = V*I*cosθ;

[0062] Where V is the amplitude of the voltage signal, I is the amplitude of the current signal, and θ is the phase difference between voltage and current.

[0063] S7: Determine whether the current pulse is in a low level state. If it is in a low level state, the FPGA processor module enters a pulse low power modulation mode. The pulse is generated by the processor FPGA according to external instructions.

[0064] S8: Determine whether the current pulse is in a high level state. If it is in a high level state, the FPGA processor module enters the pulse high power modulation mode.

[0065] S9: Determine whether the current power is in the power ramp-up phase. Figure 5 The whole climbing cycle T time is less than 15US, T1 = 0.4T, T2 = 0.6T, and the time parameter values ​​of T1 and T2 are obtained based on debugging experience. If it is in the climbing stage, it enters the climbing stage power modulation mode. If not, it enters the power reduction stage modulation mode.

[0066] S10: Determine whether the real-time value of the pulse low power reaches the set value. If it reaches it, go to the power modulation completion step. If it is higher than the set value, enter the pulse low power modulation mode.

[0067] S11: Determine whether the real-time value of the pulse high power reaches the set value. If it reaches it, go to the power modulation completion step. If it is less than the set value, enter the pulse high power modulation mode.

[0068] S12: Power ramp-up modulation mode. When the pulse is in the stage of transitioning from low level to high level, the power ramp-up modulation mode is entered to prepare for phase adjustment. In the power ramp-up stage, it is necessary to ensure that the phase difference of the two RF drive signals is rapidly close in the short period of time at the beginning of the power ramp-up stage, and then slowly adjust the phase in the remaining time to smoothly transition the power adjustment. Ideally, we expect to achieve a fast and smooth transition during the pulse power conversion process, such as Figure 2 As shown in the figure, the power output has no overshoot and no glitch interference. If this stage is not handled properly, the following will occur: Figure 4 As shown in the figure, if the output pulse power overshoots, it will be extremely detrimental to the stable operation and performance of the equipment, and will lead to a large number of defective products in production. Therefore, the fine processing of the power ramp-up stage is the key to ensuring the stability of the RF power supply performance and avoiding potential problems.

[0069] S13: Power reduction stage modulation. When high power is converted to low power, there is a process of output power reduction, which is called the power reduction stage. In the reduction stage, the RF power supply system linearly adjusts the phase difference between the two RF signals. When the phase difference between the two drive signals is larger, the system output power is smaller until it reaches the set power value.

[0070] S14: Pulse low power modulation. When modulating in low power mode, the supply voltage of the power amplifier module is not adjusted. The processor FPGA uses the PID method to adjust the phase of the two drive signals through the RF signal driving module. The larger the phase difference between the two drive signals, the lower the output RF power.

[0071] S15: Pulse high power modulation. In high power mode modulation, the phases of the two RF drive signals are at preset values ​​without adjustment. The processor FPGA adjusts the power supply voltage of the power amplifier module by using the PID method. The greater the power supply voltage of the power amplifier module, the higher the output RF power.

[0072] S16: During the ramp-up phase, adjust the power supply voltage of the power amplifier module. Figure 5 During the entire cycle T of power ramp-up, the power supply voltage of the power amplifier module is adjusted to 90% of the pulse high power. The adjusted voltage ratio is based on actual debugging experience. Adjusting the supply voltage can effectively reduce the overshoot of the output power.

[0073] S17: Determine whether it is in the early stage of the climbing phase. If so, the system enters the next step of early stage phase adjustment of the climbing phase.

[0074] S18: Determine whether it is in the late climbing stage. If so, the system enters the next step of late climbing stage phase adjustment.

[0075] S19: Phase difference adjustment in the early stage of climbing, such as Figure 5 During the T1 time of the power ramp-up phase, the system completes 80% of the phase difference adjustment of the two RF drive signals, in order to ensure that the phase difference is close to each other quickly in the short period of time at the beginning of the power ramp-up phase. Figure 5 It can be seen that the rising slope during T1 is significantly steeper than that during T2. Although the power is adjusted quickly during this period, the impact will not exceed the set value due to the low power.

[0076] S20: Phase difference adjustment in the late climbing stage, such as Figure 5 During the T2 period after the power ramp-up phase, the system completes the remaining 20% ​​phase difference adjustment. Figure 5 It can be seen that the rising slope becomes slower during the T2 time, and the power begins to be adjusted slowly, in order to achieve a smooth transition of power.

[0077] S21: Pulse power modulation is completed, and the RF power supply system repeats the steps of S4-S21 to perform pulse power modulation, so as to ensure that the entire RF power supply system can stably output pulse power.

[0078] In the entire RF power supply system, in order to ensure that there is no power overshoot during the pulse modulation process, the system's operating status must be monitored in real time when implementing the coordinated control strategy of phase and voltage. Specifically, the system needs to continuously monitor key parameters such as the power supply voltage, current, and power amplifier module temperature, while monitoring the operating temperature, input / output signals, and other conditions of other modules. Through these real-time data, the system can promptly detect potential abnormalities and immediately take protective measures, such as reducing power output or cutting off power, thereby effectively avoiding hardware damage and ensuring the safe and stable operation of the RF power supply system.

[0079] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It is obvious to those skilled in the art that the present invention is not limited to the details of the above exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic features of the present invention. Therefore, no matter from which point of view, the embodiments should be regarded as exemplary and non-restrictive. The scope of the present invention is defined by the attached claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims are included in the present invention. Any figure mark in the claims should not be regarded as limiting the claims involved.

[0080] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A radio frequency power supply system, characterized in that: It includes a radio frequency signal driving module, a power amplifier module, a power synthesis module, a power detection module and a processor module; RF signal driving module: used to output two phase-adjustable RF driving signals, each signal driving a group of power amplifiers; Power amplifier module: connected to the RF signal driving module, responsible for amplifying the driving signal to the required power level. This module contains two power amplifier modules and can adjust the power supply voltage of the power amplifier module; Power synthesis module: connected to the two power amplifier modules of the RF power amplifier, effectively superimposing the power output of the two power amplifier modules to form the final RF pulse power output; Power detection module: used to detect output power and feed back the voltage and current signals of the real-time detected output power to the processor module; Processor module: used to receive external instructions and voltage and current signals fed back by the power detection module, and automatically adjust the phase difference of the two drive signals of the RF signal drive module and the supply voltage of the power amplifier module according to the set pulse frequency and power requirements to achieve precise control of the output power.

2. A radio frequency power supply system according to claim 1, characterized in that: The transmission of the radio frequency signal in the radio frequency signal driving module adopts a differential mode. The radio frequency signal driving module uses a digital-to-analog conversion chip, which has two independent digital-to-analog conversion channels and can process two radio frequency signals at the same time.

3. A radio frequency power supply system according to claim 1, characterized in that: The power amplifier module uses a water tray high heat dissipation component.

4. A method for preventing power overshoot by pulse modulation of radio frequency power supply, characterized in that: Specifically include the following: The RF power system monitors the high power and low power states of pulse power output in real time; When low power is converted to high power, the system completes 80% phase difference adjustment of the two RF drive signals in the first 40% of the power ramp-up phase; When low power is converted to high power, the system completes the remaining 20% ​​phase difference adjustment within 60% of the time after the power ramp-up phase; During the power ramp-up phase, the power amplifier module supply voltage is modulated to 90% of the high-power voltage; When the phase difference adjustment of the two RF driving signals is completed, the supply voltage of the power amplifier module will be modulated to 100% of the voltage at high power.

5. The method for preventing power overshoot by pulse modulation of radio frequency power supply according to claim 4, characterized in that: It also includes that the pulse cycle frequency range of the pulse modulated radio frequency signal is 100HZ-10KHZ. In each pulse cycle, the radio frequency power supply system outputs high power when the pulse is at a high level and outputs low power when the pulse is at a low level.

6. The method for preventing power overshoot by pulse modulation of radio frequency power supply according to claim 4, characterized in that: It also includes that the power ramp-up phase time is less than 15us.

7. The method for preventing power overshoot by pulse modulation of radio frequency power supply according to claim 4, characterized in that: It also includes that during pulse power modulation, the phase difference adjustment process of the two RF drive signals in the power climbing stage is nonlinear.

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