Switched RF Matching Network for Fast Plasma Impedance Tracking
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Solution Overview
Problem
Conventional impedance matching networks in RF plasma processing systems fail to adjust to rapid changes in plasma load impedance due to interactions between RF and DC pulsed voltage waveforms, leading to inter-modulation distortion and undesirable variations in RF power delivery, affecting plasma processing consistency.
Innovation Solution
A tuning circuit with a first and second impedance and a signal path including an inductive element and a switch, controlled by a control input receiving a pulsed voltage waveform, allows for fast impedance matching to accommodate changing plasma load impedance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional impedance matching networks are used, then the system structure is simple, but the matching speed is slow and cannot keep up with rapid impedance changes
Solution Approach 1:
The patent implements a dynamic impedance matching network that actively adjusts matching parameters in real-time to track rapid impedance changes during DC voltage pulsing. The system transitions from static conventional matching to dynamic adaptive matching, enabling the network to respond to impedance variations at speeds matching the pulsing frequency (>100 kHz).
Solution Approach 2:
The patent incorporates feedback mechanisms that continuously monitor plasma load impedance and automatically adjust the matching network parameters accordingly. This closed-loop control enables rapid adaptation to impedance changes without manual intervention, solving the speed limitation of conventional open-loop matching systems.
2Adaptability or versatility
If DC voltage pulsing is used to control plasma sheath, then plasma processing control is improved, but inter-modulation distortion increases and power delivery efficiency decreases
Solution Approach 1:
The patent synchronizes the impedance matching network dynamics with the DC voltage pulsing frequency, enabling the matching network to adapt its parameters in sync with plasma sheath transitions. This dynamic synchronization minimizes inter-modulation distortion and reflected power by ensuring the matching network always presents the optimal impedance despite rapid plasma load changes.
3Productivity
If fast impedance matching is implemented, then power delivery efficiency is improved, but the system complexity increases
Solution Approach 1:
The patent replaces mechanical tuning components with solid-state electronic switching and control circuitry. This substitution enables faster response times and higher frequency operation (>100 kHz) while reducing mechanical wear and improving reliability. The electronic implementation achieves fast impedance matching without the complexity constraints of mechanical tuning systems.
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
The solution provides efficient impedance matching, reducing reflected power and increasing power delivery efficiency, resulting in improved plasma processing results and etch rates.
Implementation Method 1
A tuning circuit with a first and second impedance and a signal path including an inductive element and a switch, controlled by a control input receiving a pulsed voltage waveform, allows for fast impedance matching to accommodate changing plasma load impedance.
Data Source
AI summary
Some embodiments are directed to a tuning circuit. The tuning circuit generally includes: a first impedance coupled between a first terminal and a second terminal of the tuning circuit, wherein the first terminal is coupled to a generator and the second terminal is coupled to a load; a second impedance coupled between the first impedance of the tuning circuit and a reference potential node; and a signal path coupled to the first impedance or the second impedance, the signal path comprising an inductive element and a first switch coupled to the inductive element, wherein a control input of the first switch is coupled to a control input of the tuning circuit configured to receive a control signal associated with a pulsed voltage (PV) waveform.