RF Matching Box Control for Fast Plasma Impedance Matching
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Solution Overview
Problem
Existing plasma processing apparatuses face challenges in achieving rapid and efficient impedance matching due to mechanical differences and increased losses in matching boxes using variable inductors, which affect the stability and efficiency of radio-frequency power supply to plasma electrodes.
Innovation Solution
A plasma processing apparatus equipped with a matching box containing variable inductors and an efficiency map that correlates inductance values with efficiency, allowing for real-time adjustment of inductance to optimize impedance matching and power supply, thereby compensating for mechanical differences and reducing losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a matching box with variable inductors is used for impedance matching, then the adaptability to different plasma conditions is improved, but the loss of energy increases due to mechanical differences and component variations
Solution Approach 1:
The patent changes the inductance parameter of the variable inductor dynamically based on the efficiency map to optimize the balance between adaptability and energy loss. By selecting specific inductance values from the efficiency map rather than using any arbitrary value, the system maintains high adaptability while minimizing energy losses in the matching box.
2Device complexity
If traditional impedance matching methods are used without efficiency consideration, then the device complexity is reduced, but the productivity decreases due to slower convergence and more iterations required
Solution Approach 1:
The efficiency map is pre-calculated and stored before actual plasma processing, containing optimal inductance combinations for various operating conditions. This preliminary action allows the control system to quickly query and apply pre-determined optimal parameters during impedance matching, significantly improving matching speed without adding complex real-time calculation capabilities to the control system.
3Reliability
If real-time efficiency monitoring and adjustment is implemented, then the reliability of plasma generation is improved, but the device complexity increases due to additional sensors and control logic
Solution Approach 1:
The system implements feedback by monitoring the actual plasma conditions and comparing them with the efficiency map data. The control unit continuously adjusts the variable inductor settings based on feedback from plasma parameters, ensuring stable plasma generation. This feedback mechanism is integrated into the existing control architecture, avoiding excessive complexity increase while maintaining high reliability.
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 enables rapid impedance matching, stabilizes plasma generation, and enhances the efficiency of radio-frequency power supply to plasma electrodes, improving the consistency and quality of plasma processing.
Implementation Method 1
a radio-frequency power supply that applies radio-frequency power to a substrate holder inside a chamber
Implementation Method 2
a plasma generator that generates a plasma from a gas using the radio-frequency power
Data Source
AI summary
The plasma processing apparatus includes a radio-frequency power supply, a pair of plasma electrodes, a matching box located between the pair of plasma electrodes and the radio-frequency power supply and having an impedance matching circuit including a first variable inductor and a second variable inductor, and a control unit. The control unit executes performing impedance matching by varying the inductance of the first variable inductor and the inductance of the second variable inductor, obtaining the efficiency of the matching box based on the inductance of the first variable inductor and the inductance of the second variable inductor after the impedance matching and the efficiency map, and calculating output power of the radio-frequency power supply based on the obtained efficiency of the matching box and supply power supplied to the plasma electrodes, and controlling the output power of the radio-frequency power supply based on the calculated output power.