State-Based RF Power and Frequency Adjustment for Plasma Impedance
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Solution Overview
Problem
Plasma processing systems face challenges in quickly responding to changes in plasma impedance due to the slow response time of impedance matching circuits, which can negatively affect processes like etching and deposition within the plasma chamber.
Innovation Solution
Implementing a state-based adjustment of power and frequency for RF signals generated by multiple RF sources, where the power and frequency values are predetermined for specific states of a digital pulsing signal, allowing for quicker reaction to changes in plasma impedance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If impedance matching circuit is used to match plasma impedance, then impedance matching is achieved, but response time to change in plasma impedance is slow
Solution Approach 1:
The system pre-establishes multiple RF signal configurations (different frequencies and power levels) corresponding to different plasma impedance states. When a change in plasma impedance is detected, the system can immediately switch to the pre-configured signal parameters without performing real-time impedance matching calculations, thus reducing response time while maintaining reliable impedance matching.
Solution Approach 2:
The patent implements dynamic adjustment of RF signal frequency and power levels based on detected plasma impedance changes. The system continuously monitors plasma impedance and dynamically switches between pre-configured RF signal states, allowing the system to adapt quickly to changing plasma conditions without the slow response of traditional impedance matching circuits.
2Adaptability or versatility
If multiple RF signals are provided to generate plasma, then plasma generation capability is enhanced, but complexity of power and frequency control increases
Solution Approach 1:
The control system is divided into multiple independent RF signal generators, each capable of operating at different frequencies and power levels. Each generator has its own control logic that independently responds to plasma impedance changes, allowing the system to manage complexity by distributing control functions across multiple modular units rather than requiring a single complex control system.
Solution Approach 2:
The system controls multiple RF signals by changing their operating parameters (frequency and power levels) based on plasma impedance states. Instead of complex real-time coordination, each RF signal generator switches between pre-defined parameter sets, simplifying control while maintaining the ability to generate and maintain plasma under various conditions.
Data Source
AI summary
Systems and methods for state-based adjustment of power and frequency are described. A primary generator of a system includes a primary power supply for supplying a primary radio frequency (RF) signal to an electrode. The primary generator further includes an automatic frequency control (AFC) to provide a first frequency input to the primary power supply when a pulsed signal is in a first state. A secondary generator of the system includes a secondary power supply for supplying a secondary RF signal to the electrode. The secondary generator also includes an AFC to provide a second frequency input to the secondary power supply when the pulsed signal is in the first state. The secondary generator includes an AFC to provide a third frequency input to the secondary power supply when the pulsed signal is in a second state. The system includes a digital pulsing source for generating the pulsed signal.