Pulse Tracking RF Match Controller for Plasma Chamber Impedance
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Solution Overview
Problem
Conventional RF matches cannot be actively tuned during pulse mode operation in plasma processing systems, leading to reflected power and reduced power transfer efficiency due to fixed impedance, which is suboptimal for varying plasma chamber impedance.
Innovation Solution
A system and method for actively tuning an RF matching network during pulsed mode operation by using a phase and magnitude detector circuit to sense signals, a pulse tracking circuit to generate tracked error signals, and a match controller to adjust impedance in response, ensuring optimal impedance matching between the RF generator and plasma chamber.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the RF match impedance is fixed after tuning in continuous mode, then the RF match structure is simple, but reflected power increases during pulse mode operation due to plasma chamber impedance variations
Solution Approach 1:
The patent implements dynamic impedance tuning by enabling the RF match to continuously adjust its impedance parameters during pulse mode operation. The system transitions from a fixed impedance configuration to a dynamic one where the match network responds to real-time plasma chamber impedance variations, thereby minimizing reflected power while maintaining operational simplicity through automated control.
Solution Approach 2:
The system employs feedback mechanisms by monitoring the plasma chamber impedance during pulse mode operation and using this information to actively tune the RF match impedance. The controller receives feedback signals about the plasma state and adjusts the match network parameters accordingly, creating a closed-loop system that reduces reflected power without requiring complex manual intervention.
2Reliability
If the RF match continuously follows phase and magnitude signals, then the impedance tracking is continuous, but the RF match moves to a non-optimum position reducing power transfer efficiency
Solution Approach 1:
The patent implements periodic impedance tuning synchronized with the pulse mode operation cycles. Instead of continuous adjustment that causes instability, the system performs impedance measurements and tuning actions at specific intervals within each pulse cycle, allowing the plasma chamber to stabilize between adjustments. This periodic approach maintains reliable impedance tracking while preventing the RF match from drifting to non-optimum positions.
Solution Approach 2:
The system performs preliminary impedance measurements during the off-period of pulse cycles before the next power delivery phase. By preparing and pre-tuning the RF match impedance during intervals when the plasma is not actively receiving power, the system ensures optimal impedance matching is ready before each power delivery pulse, maximizing power transfer efficiency without disrupting the active plasma process.
3Productivity
If the RF generator operates in pulse mode, then the plasma processing efficiency is improved, but conventional RF matches cannot be actively tuned leading to reflected power
Solution Approach 1:
The patent replaces traditional mechanical impedance tuning mechanisms with electronic control systems that can operate during pulse mode. Instead of physically adjusting matching components during operation, the system uses electronic circuits to dynamically adjust impedance parameters through electrical signals, enabling active tuning capability that complements pulse mode operation without mechanical constraints.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach reduces reflected power and enhances power transfer efficiency by dynamically adjusting the RF matching network impedance in real-time, even during pulse mode operations, thereby improving the overall performance of plasma processing systems.
Implementation Method 1
sensing a pulsing process signal with a phase and magnitude detector circuit
Implementation Method 2
sensing a pulsing process signal with a phase and magnitude detector circuit
Implementation Method 3
The RF match may be tuned, i.e., the impedance may be varied, to make the output impedance of the RF match be the complex conjugate of the plasma chamber's impedance. Tuning the RF match reduces reflected power from the plasma chamber and/or the RF match, thereby increasing the power transferred from the RF generator to the plasma chamber
Data Source
AI summary
A plasma processing system may include a radio frequency (RF) generator configured to supply a pulsing process signal to a target in a plasma processing chamber via a RF matching network. A phase and magnitude detector circuit is coupled to the RF generator and configured to sense the pulsing process signal and output a magnitude error signal and a phase error signal. A pulse tracking circuit is electrically coupled to the phase and magnitude detector circuit and configured to receive the magnitude error signal and the phase error signal and output a tracked magnitude signal and a tracked phase signal. A match controller is electrically coupled to the pulse tracking circuit and the RF matching network and configured to receive the tracked magnitude signal and the tracked phase signal and vary an impedance of the RF matching network in response to the tracked magnitude and phase signals.