Dual-Frequency RF Power Supply Synchronization for Plasma Matching
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Solution Overview
Problem
High-frequency power supply apparatuses used in plasma processing devices experience intermodulation distortion, leading to fluctuating reflected wave power due to differing fundamental frequencies, which hampers efficient power supply when frequency modulation control is applied.
Innovation Solution
The apparatus includes a first and second high-frequency power supply with matching devices that generate a timing control signal based on detected high-frequency voltages, allowing the first power supply to perform frequency modulation on its output voltage using a modulation signal synchronized with the second power supply's frequency, thereby reducing intermodulation distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If frequency modulation control is performed on the first high-frequency voltage using a pseudo-generated modulation signal, then intermodulation distortion may be reduced, but the reflected wave power reduction effect deteriorates due to cycle mismatch
Solution Approach 1:
The patent introduces a feedback mechanism where the cycle of the second high-frequency voltage is detected and used to adjust the modulation signal cycle. The detection unit measures the actual cycle of the second power supply's output, and the control unit uses this information to set the modulation signal cycle to match, ensuring synchronized frequency modulation that effectively reduces reflected wave power while maintaining intermodulation distortion suppression.
Solution Approach 2:
The patent dynamically adjusts the parameter of the modulation signal (its cycle) based on the detected cycle of the second high-frequency voltage. By changing the modulation signal cycle to match the second power supply's output cycle, the system achieves accurate frequency modulation control that simultaneously reduces intermodulation distortion and minimizes reflected wave power.
2Ease of operation
If a modulation signal with fixed frequency equal to the second fundamental frequency is generated, then frequency modulation control can be implemented, but the modulation signal cycle does not match the second power supply output cycle
Solution Approach 1:
The patent employs feedback by detecting the actual cycle of the second high-frequency voltage and using this information to adjust the modulation signal cycle. This ensures that the modulation signal remains synchronized with the second power supply's output, maintaining both ease of operation and measurement precision.
Solution Approach 2:
The patent makes the modulation signal cycle dynamic rather than fixed. The control unit adjusts the modulation signal cycle in real-time based on the detected cycle of the second power supply's output, allowing the system to adapt to variations and maintain precise cycle synchronization while preserving operational simplicity.
3Adaptability or versatility
If two high-frequency power supplies with different fundamental frequencies are used, then plasma generation and ion acceleration can be achieved, but intermodulation distortion occurs causing reflected wave power fluctuation
Solution Approach 1:
The patent converts the harmful intermodulation distortion effect into a beneficial control mechanism. By detecting the cycle of the second power supply's output and using it to synchronize the modulation signal of the first power supply, the system transforms the intermodulation phenomenon into a means for achieving precise frequency modulation control that reduces reflected wave power while maintaining plasma generation and ion acceleration capabilities.
Data Source
AI summary
A high-frequency power supply apparatus includes the following elements. A first power supply outputs a first high-frequency voltage with a first fundamental frequency. A second power supply outputs a second high-frequency voltage with a second fundamental frequency lower than the first fundamental frequency. A second matching device is connected between the second power supply and the load. The second matching device generates a timing control signal with a frequency lower than the second fundamental frequency. The first power supply generates a modulation signal by applying a start phase and a frequency shift amount to a modulation fundamental wave signal whose frequency is equal to the second fundamental frequency. The start phase is applied to the modulation fundamental wave signal in accordance with an input timing of the timing control signal. The first power supply performs frequency modulation on the first high-frequency voltage by using the modulation signal.