Radio frequency power supply overheating protection method and device

Abstract

The invention relates to a radio frequency power supply overheating protection method and device. The method comprises the following steps: monitoring the temperature of a heating part in the radio frequency power supply, and respectively comparing the temperature with a set first temperature critical value and a set second temperature critical value in real time; when it is judged that the temperature of the heating component is larger than the first temperature critical value, the radio-frequency power supply is controlled to run in a derated mode till the temperature of the heating component is smaller than the second temperature critical value, the output power of the radio-frequency power supply is gradually adjusted to restore to be before derating, and the first temperature critical value is larger than the second temperature critical value. According to the invention, sudden shutdown of the radio frequency power supply can be avoided while overheating protection of the radio frequency power supply is realized, and continuity of a production process and stability of output power are ensured.

Description

Technical Field

[0001] This invention relates to the field of radio frequency power supply technology, and in particular to a method and apparatus for overheat protection of radio frequency power supplies. Background Technology

[0002] Radio frequency (RF) power supplies are core components of critical equipment used in plasma processes (such as etching and deposition), induction heating, and medical ablation. Their internal power amplification modules and matching networks generate significant heat due to power loss during the conversion of DC power into high-frequency, high-power RF energy. To ensure equipment safety, existing RF power supplies are generally designed with thermal protection features.

[0003] Currently, the mainstream protection method involves installing normally closed temperature switches or simple temperature detection circuits in locations such as heat sinks. When the temperature at the monitored point reaches a fixed, typically high, limit (e.g., 85°C), the temperature switch closes or the circuit is triggered, generating a shutdown signal that directly and forcibly cuts off the power output of the RF power supply, achieving "hard shutdown" protection. This "one-size-fits-all" hard shutdown protection strategy has significant drawbacks:

[0004] (1) Risk of process interruption: In precision processes such as semiconductor manufacturing, a sudden interruption of radio frequency power can lead to the scrapping of wafers being processed, resulting in huge economic losses.

[0005] (2) Low production efficiency: After the equipment is shut down, it must be allowed to cool down to a safe temperature before it can be restarted. This waiting process will seriously affect the overall production cycle and efficiency.

[0006] (3) Reduced reliability: Because the protection threshold is set too high to avoid accidental activation, the power supply will operate at a high temperature close to the limit for a long time. This will accelerate the aging of internal semiconductor devices and capacitors and shorten the overall service life of the power supply. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to provide a method and device for overheat protection of radio frequency power supply, which can prevent the radio frequency power supply from suddenly shutting down while realizing overheat protection of radio frequency power supply, and ensure the continuity of production process and the stability of output power.

[0008] The technical solution adopted by this invention to solve its technical problem is: to provide a method for overheat protection of radio frequency power supply, comprising:

[0009] Monitor the temperature of the internal heating components of the RF power supply and compare it in real time with the set first and second temperature thresholds.

[0010] When the temperature of the heating component is determined to be greater than the first temperature threshold, the RF power supply is controlled to operate at a reduced rate until the temperature of the heating component is less than the second temperature threshold. Then, the output power of the RF power supply is gradually adjusted to restore it to the level before the reduction, and the first temperature threshold is greater than the second temperature threshold.

[0011] Furthermore, the control of the RF power supply to operate at a derating rate is achieved by gradually adjusting the output power of the RF power supply to reduce it to a set safe power value.

[0012] Furthermore, the gradual adjustment of the output power of the RF power supply is achieved by linearly adjusting the bias voltage of the power amplifier transistor.

[0013] Furthermore, the gradual adjustment of the output power of the RF power supply is achieved by gradually adjusting the duty cycle of the PWM control signal.

[0014] Furthermore, the set power safety value is 50% of the rated output power or 70% of the output power before derating.

[0015] Furthermore, the heat-generating component includes a power amplifier tube substrate, a high-frequency transformer, or an output matching network.

[0016] The present invention also provides an overheat protection device for radio frequency power supplies, comprising:

[0017] RF power supply;

[0018] Temperature monitoring module, used to monitor the temperature of heat-generating components inside the RF power supply;

[0019] The comparison module is used to set a first temperature threshold and a second temperature threshold, and compare them with the temperature of the heating element in real time. When it is determined that the temperature of the heating element is greater than the first temperature threshold, a first control signal is output, and when it is determined that the temperature of the heating element is less than the second temperature threshold, a second control signal is output.

[0020] The power regulation module is connected to the main power amplification circuit of the RF power supply. It is used to control the RF power supply to operate at a derating rate in response to the first control signal, and then gradually adjusts the output power of the RF power supply to restore it to the level before the derating rate after receiving the second control signal.

[0021] Furthermore, the power regulation module controls the RF power supply to operate at a derating rate by gradually adjusting the output power of the RF power supply to reduce it to a set safe power value.

[0022] Furthermore, the power adjustment module is connected to the power amplifier tube of the main power amplifier circuit of the RF power supply, and the output power of the RF power supply is gradually adjusted by linearly adjusting the bias voltage of the power amplifier tube.

[0023] Furthermore, the power adjustment module is connected to the PWM controller of the main power amplification circuit of the RF power supply, and gradually adjusts the output power of the RF power supply by gradually adjusting the duty cycle of the PWM control signal.

[0024] Beneficial effects

[0025] Due to the adoption of the above technical solutions, this invention has the following advantages and positive effects compared with the prior art: This invention uses "derating operation" instead of "shutdown protection." Through a dual-temperature critical value hysteresis comparison control strategy, when the temperature of the internal heating component of the RF power supply exceeds the first temperature critical value, a derating operation mechanism is triggered instead of directly interrupting the output. This ensures that processes with extremely high continuity requirements, such as semiconductor etching and thin film deposition, are not interrupted, avoiding work-in-process reports and production line restart costs caused by shutdowns. This invention designs dynamic power adjustment and adaptive recovery logic. When the temperature of the heating component exceeds the first temperature critical value, the derating operation mechanism is triggered immediately. When the temperature drops below the second temperature critical value, the power is gradually restored to its original level through an adjustment mechanism. Instead of undergoing a long "shutdown-cooling-restart" cycle, this invention provides real-time heat dissipation during continuous low-power operation. While ensuring the timeliness of overheat protection, it effectively avoids frequent output power oscillations caused by minor temperature fluctuations near a single critical point, thus guaranteeing system stability. Through an active power intervention mechanism, the operating temperature of core heat-generating components is controlled within a safe range. Combined with a power smoothing adjustment strategy, this allows the RF power supply to maintain signal integrity while operating at a derating rate. This reduces deviations in process parameters caused by high-temperature operation and large fluctuations in output power, and enables core components to operate in a healthier temperature range for extended periods, significantly slowing down device aging and thereby improving the long-term stability and lifespan of the entire RF power supply. Attached Figure Description

[0026] Figure 1 This is a flowchart of the first embodiment of the present invention;

[0027] Figure 2 This is a schematic diagram of the structure of the second embodiment of the present invention. Detailed Implementation

[0028] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0029] The first embodiment of the present invention relates to a method for overheat protection of a radio frequency power supply, such as... Figure 1As shown, the process includes the following steps: monitoring the temperature of the internal heating component of the RF power supply and comparing it in real time with the set first temperature threshold T1 and second temperature threshold T2; when it is determined that the temperature of the heating component is greater than the first temperature threshold T1, the RF power supply is controlled to operate at a derating rate until the temperature of the heating component is less than the second temperature threshold T2, and then the output power of the RF power supply is gradually adjusted to restore it to the level before derating.

[0030] The core function of an RF power supply is to generate and regulate RF energy, mainly including power input, RF energy generation, and impedance matching. RF energy generation is the core component of the RF power supply, comprising the main power control circuit, which consists of switching transistors, high-frequency transformers, power amplifier transistors, RF synthesizers / dividers, and main control and signal processing circuits. The PWM (Pulse Width Modulation) wave generated by the main control signal drives the switching transistors. The switching transistors (such as MOSFETs) are the core of the power converter (such as a DC-DC converter). The main control circuit controls the on / off time of the switching transistors by adjusting the duty cycle (i.e., pulse width) of the PWM signal, thereby precisely adjusting the DC voltage or current output by the converter. This DC energy is then supplied to the power amplifier transistors. The power amplifier transistors (such as LDMOS transistors), as the core of RF amplification, operate in specific high-frequency switching states (such as Class E or Class F), responsible for efficiently converting the regulated DC power into high-power RF energy. The operating state (such as gain and efficiency) of the power amplifier transistors is significantly affected by their bias voltage.

[0031] Therefore, in this invention, when the temperature is too high and derating is required:

[0032] One approach is to control the output of the power converter by gradually adjusting the duty cycle of the PWM signal, thereby reducing the power supplied to the power amplifier transistor.

[0033] Another approach is to directly change the amplification state (such as gain or efficiency) of the power amplifier tube by linearly adjusting its bias voltage, thereby reducing its RF output power.

[0034] Both of these methods are effective ways to achieve gradual adjustment of the final output power of the radio frequency power supply for overheat protection in this invention.

[0035] Key heat-generating components include the power amplifier tube substrate, high-frequency transformer, and output matching network. The temperature of these components can be monitored in real time and continuously by tightly mounting a high-precision temperature sensor (such as a PT100 RTD or a digital temperature sensor) on the key heat-generating component inside the RF power supply, and the temperature of the sensor can be converted into a standardized electrical signal.

[0036] The two temperature protection thresholds T1 and T2 are settable, and T1 > T2. Users can flexibly adjust the protection strategy according to different load characteristics, ambient temperature and process requirements to achieve the optimal balance.

[0037] In practice, the critical values ​​T1 and T2 can be set and adjusted via host computer software, device panel, or internal potentiometer to adapt to different application environments and load requirements. For example, T1 can be set to 75°C and T2 can be set to 68°C.

[0038] T2 is the critical value for derating recovery temperature. Its set value is lower than T1, which is the critical value for overheat derating temperature. It is used to form hysteresis control to prevent frequent power jumps when the temperature fluctuates around T1.

[0039] Temperature comparison can be achieved through a comparator circuit, which continuously compares the real-time temperature signal from the temperature monitoring module with the set T1 and T2, and outputs a logic control signal based on the comparison result.

[0040] When the real-time temperature is below T1, the RF power supply outputs power normally according to the user-set power. When the real-time temperature exceeds T1, the comparator outputs a trigger signal (i.e., the first control signal), which immediately triggers derating protection. The main power control loop smoothly reduces the output power of the RF power supply to a preset "safe operating power". Simultaneously, the system can output an alarm signal. The "safe operating power" can be set to 50% of the rated power or 70% of the user-set original power.

[0041] In some preferred embodiments, to prevent sudden power or voltage changes from causing RF load detuning and process parameter fluctuations (such as in plasma etching or thin film deposition, where sudden power changes can lead to plasma density fluctuations, resulting in uneven etching rates or thin film thickness deviations, and increased byproducts caused by changes in process gas dissociation rates), the output power of the RF power supply needs to be gradually adjusted. Furthermore, different power adjustment strategies can be adopted depending on the selected key heat-generating components. Specifically, this can be achieved by gradually adjusting the duty cycle of the PWM control signal (e.g., for all heat-generating components), or by linearly changing the bias voltage of the power amplifier transistor (e.g., for the power amplifier transistor), or by using both methods simultaneously.

[0042] In derating operation, when the real-time temperature drops below T2 due to power reduction, the comparator outputs a recovery signal (i.e., the second control signal). This signal, through the main power control loop, smoothly restores the RF power supply's output power to the user's original set value, and the alarm signal is canceled. Through this scheme, the RF power supply constructs an intelligent "temperature-power" negative feedback regulation loop.

[0043] A preferred embodiment 1 of this implementation: an overheat protection method for radio frequency power supply based on PWM duty cycle adjustment.

[0044] Specifically, the following steps are included:

[0045] A high-precision temperature sensor is installed on the high-frequency transformer or output matching network of the RF power supply to collect the temperature in real time and convert it into an electrical signal, which is then input to the analog input port of the microcontroller.

[0046] The host computer sets a first temperature threshold value T1 and a second temperature threshold value T2, and T2... <T1;

[0047] The temperature signal is compared with two temperature thresholds in real time to generate a derating trigger signal (temperature ≥ T1) or a recovery signal (temperature ≤ T2).

[0048] Adjusting the operating state of the RF power supply based on the generated signal, specifically including:

[0049] Normal operation: Outputs a PWM signal with a fixed duty cycle to control the RF power supply to operate at the power set by the user;

[0050] Trigger derating: Upon receiving a derating signal, gradually reduce the PWM duty cycle to smoothly reduce the output power to a preset safe power value (such as 50%-70% of the rated power), and activate the alarm mechanism at the same time;

[0051] Exit derating: After derating for a period of time, when a recovery signal is received, the PWM duty cycle is gradually restored to its original value, the power returns to the normal level, and the alarm is cleared.

[0052] When adjusting the PWM duty cycle, the target adjustment power can be used as the modulation signal, the triangular wave as the carrier signal, and the target adjustment power can be set to gradually decrease with a fixed step size, so as to smoothly increase or decrease the duty cycle of the generated PWM signal.

[0053] A preferred embodiment 2 of this implementation: an overheat protection method for radio frequency power supply based on power transistor bias voltage regulation.

[0054] Specifically, the following steps are included:

[0055] A temperature sensor is deployed on the power amplifier transistor substrate to continuously monitor the junction temperature;

[0056] Pre-store configurable overheat derating threshold T1 and recovery threshold T2;

[0057] The junction temperature is compared with the two thresholds in real time to generate a derating trigger signal (junction temperature ≥ T1) or a recovery signal (junction temperature ≤ T2).

[0058] Adjusting the operating state of the RF power supply based on the generated signal, specifically including:

[0059] Normal state: The bias voltage of the power transistor is maintained at the optimal operating point, and the power supply outputs rated power;

[0060] Triggered derating: When the temperature exceeds T1, the regulating circuit linearly reduces the bias voltage of the power transistor, reduces its conduction efficiency, and gradually reduces the output power to a safe value, while sending a fault signal.

[0061] Exiting derating: After the temperature drops below T2, the bias voltage gradually returns to its initial value, the power is restored to the user-set value, and the system returns to normal operating mode.

[0062] A second embodiment of the present invention relates to an overheat protection device for a radio frequency power supply, comprising:

[0063] RF power supply;

[0064] Temperature monitoring module, used to monitor the temperature of heat-generating components inside the RF power supply;

[0065] The threshold setting and comparison module is used to set a first temperature threshold and a second temperature threshold, and compare them with the temperature of the heating element in real time. When it is determined that the temperature of the heating element is greater than the first temperature threshold, a first control signal is output, and when it is determined that the temperature of the heating element is less than the second temperature threshold, a second control signal is output.

[0066] The power regulation module is connected to the main power amplification circuit of the RF power supply. It is used to control the RF power supply to operate at a derating rate in response to the first control signal, and then gradually adjusts the output power of the RF power supply to restore it to the level before the derating rate after receiving the second control signal.

[0067] The key heat-generating components of an RF power supply include the power amplifier tube substrate, the high-frequency transformer, and the output matching network. The temperature monitoring module can monitor the temperature of the detection point in real time and continuously by tightly mounting a high-precision temperature sensor (such as a PT100 RTD or a digital temperature sensor) on the key heat-generating components inside the RF power supply, and convert it into a standardized electrical signal.

[0068] More specifically, the threshold setting and comparison module is one of the core components of the over-temperature protection function, including:

[0069] A settable "overheat derating temperature threshold T1": This threshold value can be set and adjusted via host computer software, device panel or internal potentiometer to adapt to different application environments and load requirements, such as 75°C.

[0070] A configurable "derating recovery temperature threshold T2": This threshold is lower than T1 (configurable to 68°C) and is used to form hysteresis control to prevent frequent power jumps when the temperature fluctuates around T1;

[0071] A comparator circuit continuously compares the real-time temperature signal from the temperature monitoring module with the set T1 and T2, and outputs a logic control signal based on the comparison result.

[0072] The power regulation module is connected to the main power control loop of the RF power supply. It adjusts the operating state of the RF power supply in response to the control signal output by the threshold setting and comparison module, specifically including:

[0073] During normal operation: When the real-time temperature is lower than T1, this module will not intervene, and the RF power supply will output normally according to the power set by the user;

[0074] When derating protection is triggered: When the real-time temperature exceeds T1, the comparator outputs a trigger signal, and the power regulation module immediately sends a command to the main power control loop to smoothly reduce the output power of the RF power supply to a preset "safe operating power" (such as reducing it to 50% of the rated power or 70% of the user-set original power); at the same time, the system can output an alarm signal.

[0075] When exiting derating mode: In derating mode, when the real-time temperature drops below T2 due to power reduction, the comparator outputs a recovery signal, and the power regulation module instructs the main power control loop to smoothly restore the output power to the user's original set value, and the alarm signal is canceled.

[0076] Through the above scheme, the RF power supply constructs an intelligent "temperature-power" negative feedback regulation loop.

[0077] In some preferred embodiments, the output power can also be progressively adjusted by gradually changing the duty cycle of the PWM control signal or by linearly changing the bias voltage of the power transistor. Furthermore, different power adjustment strategies can be adopted depending on the selected key heat-generating components. For example, for all heat-generating components, the duty cycle of the PWM control signal can be gradually adjusted; for the power amplifier transistor, the bias voltage of the power amplifier transistor can be linearly changed. Both methods can also be used simultaneously for adjustment.

[0078] A preferred embodiment 3 of this implementation: an overheat protection device for radio frequency power supply.

[0079] Specifically, it includes:

[0080] Temperature monitoring module: A PT1000 RTD is installed on the variable capacitor housing of the output matching network, and the signal is amplified and then connected to the threshold setting and comparison module;

[0081] Threshold setting and comparison module: Set T1=70°C, T2=63°C; Process the temperature signal in real time through a comparator to generate a derating signal (T≥T1) and a recovery signal (T≤T2);

[0082] Power regulation module: Employs a composite regulation strategy.

[0083] When the temperature is ≥70°C, the output power is first reduced to 75% of the user-set power by adjusting the PWM duty cycle;

[0084] If the temperature continues to rise to 75°C, the bias voltage of the power transistor will be reduced linearly and synchronously to further reduce the power to 50% of the user-set power.

[0085] When the temperature is ≤63°C, the power is smoothly restored to its original level in two steps, following the order of "first restore the bias voltage, then restore the PWM duty cycle", to avoid overshoot caused by single adjustment.

Claims

1. A method for overheat protection of an RF power supply, characterized in that, include: Monitor the temperature of the internal heating components of the RF power supply and compare it in real time with the set first and second temperature thresholds. When the temperature of the heating component is determined to be greater than the first temperature threshold, the RF power supply is controlled to operate at a reduced rate until the temperature of the heating component is less than the second temperature threshold. Then, the output power of the RF power supply is gradually adjusted to restore it to the level before the reduction, and the first temperature threshold is greater than the second temperature threshold.

2. The method according to claim 1, characterized in that, The controlled RF power supply de-rating operation is achieved by gradually adjusting the output power of the RF power supply to reduce it to a set safe power value.

3. The method according to claim 2, characterized in that, The gradual adjustment of the RF power supply's output power is achieved by linearly adjusting the bias voltage of the power amplifier transistor.

4. The method according to claim 2, characterized in that, The gradual adjustment of the RF power supply's output power is achieved by gradually adjusting the duty cycle of the PWM control signal.

5. The method according to claim 1, characterized in that, The set power safety value is 50% of the rated output power or 70% of the output power before derating.

6. The method according to claim 1, characterized in that, The heat-generating components include the substrate of the power amplifier tube, a high-frequency transformer, or an output matching network.

7. An overheat protection device for radio frequency power supplies, characterized in that, include: RF power supply; Temperature monitoring module, used to monitor the temperature of heat-generating components inside the RF power supply; The comparison module is used to set a first temperature threshold and a second temperature threshold, and compare them with the temperature of the heating element in real time. When it is determined that the temperature of the heating element is greater than the first temperature threshold, a first control signal is output, and when it is determined that the temperature of the heating element is less than the second temperature threshold, a second control signal is output. The power regulation module is connected to the main power amplification circuit of the RF power supply. It is used to control the RF power supply to operate at a derating rate in response to the first control signal, and then gradually adjusts the output power of the RF power supply to restore it to the level before the derating rate after receiving the second control signal.

8. The apparatus according to claim 7, characterized in that, The power regulation module controls the RF power supply to operate at a derating rate by gradually adjusting the output power of the RF power supply to reduce it to a set safe power value.

9. The apparatus according to claim 8, characterized in that, The power adjustment module is connected to the power amplifier tube of the main power amplifier circuit of the RF power supply, and gradually adjusts the output power of the RF power supply by linearly adjusting the bias voltage of the power amplifier tube.

10. The apparatus according to claim 8, characterized in that, The power adjustment module is connected to the PWM controller of the main power amplification circuit of the RF power supply, and gradually adjusts the output power of the RF power supply by gradually adjusting the duty cycle of the PWM control signal.

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