Synchronized RF Power Delivery for Plasma Etching Impedance Control
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Solution Overview
Problem
Conventional RF power delivery systems for plasma etching face challenges in efficiently controlling power delivery to plasma chambers due to impedance fluctuations, leading to reduced reliability and increased costs, as they struggle to accurately manage power and frequency adjustments in response to dynamic load conditions.
Innovation Solution
The implementation of a RF generator system with a power controller that generates control signals to adjust the power and frequency of RF signals based on trigger signals, synchronizing the source RF generator with the bias RF generator to optimize power delivery during specific portions of the bias signal, and using matching networks to minimize reflected power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional RF power delivery systems control power and frequency adjustments in response to dynamic load conditions, then power delivery efficiency is reduced, but system complexity and cost increase
Solution Approach 1:
The patent applies preliminary action by pre-synchronizing the source RF generator with the bias RF generator using trigger signals before power delivery issues occur. The synchronization is established in advance through control signals that coordinate the operational phases of both generators, allowing the system to proactively maintain optimal power delivery conditions rather than reactively adjusting to impedance fluctuations.
2Reliability
If RF power delivery systems use dynamic control to manage impedance fluctuations, then reliability improves, but power delivery efficiency decreases
Solution Approach 1:
The patent implements feedback mechanisms where the power controller continuously monitors the operational state of the bias RF generator and uses trigger signals to provide real-time feedback to the source RF generator. This feedback loop enables the system to dynamically adjust and maintain synchronization, ensuring reliable power delivery while maximizing efficiency by coordinating power delivery with the actual load conditions.
Solution Approach 2:
The system performs preliminary synchronization actions by establishing phase coordination between generators before impedance fluctuations cause reliability issues. The trigger signals are generated in advance to pre-position the source RF generator's output in optimal phases, proactively preventing power delivery inefficiencies rather than reacting to them.
3Power
If the system synchronizes source RF generator with bias RF generator using control signals, then forward power is maximized, but reflected power increases
Solution Approach 1:
The patent applies periodic action through the use of trigger signals that operate in rhythmic cycles synchronized with the bias RF generator's operational phases. These periodic trigger signals continuously reset and maintain the phase relationship between generators, creating a repeating pattern of optimal power delivery that maximizes forward power while minimizing reflected power through coordinated cyclic operation.
Data Source
AI summary
A radio frequency (RF) generator system includes first and second RF power sources, each RF power source applying a respective RF signal and second RF signal to a load. The first RF signal is applied in accordance with the application of the second RF signal. The application of the first RF signal is synchronized to application of the second RF signal. The first RF signal may be amplitude modulated in synchronization with the second RF signal, and the amplitude modulation can include blanking of the first RF signal. A frequency offset may be applied to the first RF signal in synchronization with the second RF signal. A variable actuator associated with the first RF power source may be controlled in accordance with the second RF signal.