Impedance Matching Device Using Pre-Calculated Capacitor Positions
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Solution Overview
Problem
Existing impedance matching devices in plasma processing apparatuses face challenges in efficiently matching impedance due to fluctuations in plasma load impedance, often resulting in incomplete matching and unnecessary operations like hunting, due to differences between theoretical and actual circuit models.
Innovation Solution
The method involves calculating output impedance in a theoretical circuit model, simulating the load side circuit configuration, and controlling actual variable components to match the calculated values, allowing for simultaneous adjustment of first and second variable capacitors to converge to a matching point, reducing the number of repetitions and avoiding hunting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional impedance matching devices use separate adjustment of variable capacitors based on theoretical circuit models, then the device structure is simple, but the matching precision deteriorates due to differences between theoretical and actual circuit models
Solution Approach 1:
The patent performs preliminary measurement of actual circuit parameters (inductance, capacitance, resistance) before impedance matching operation. These measured values are stored and used to create an accurate circuit model that reflects the actual device characteristics, eliminating the need to rely on theoretical models that differ from reality.
Solution Approach 2:
The patent implements a feedback mechanism where the measured input impedance is continuously monitored, and the variable capacitor positions are adjusted based on the difference between measured and target impedance values. This closed-loop control ensures high matching precision by constantly comparing actual performance with desired performance.
2Reliability
If impedance matching devices perform repeated adjustments to achieve matching, then the matching completeness improves, but the time consumption increases due to hunting operations
Solution Approach 1:
The patent performs preliminary measurement and calculation of optimal variable capacitor positions before actual matching operation. By pre-calculating the required adjustments based on measured circuit parameters and target impedance, the system achieves matching in fewer steps without repeated hunting operations.
Solution Approach 2:
The patent replaces the traditional trial-and-error mechanical adjustment process with a calculation-based determination of variable capacitor positions. Instead of repeatedly adjusting capacitors based on feedback alone, the system calculates the exact positions needed based on measured parameters and circuit theory, eliminating hunting behavior.
3Adaptability or versatility
If the impedance matching device uses measured input impedance values, then the adaptability to actual plasma load changes improves, but the calculation complexity increases
Solution Approach 1:
The patent replaces complex iterative calculation processes with direct calculation methods. By measuring actual circuit parameters once and using these values in analytical calculations to determine variable capacitor positions, the system achieves adaptability to plasma load changes without requiring complex real-time iterative computations.
Data Source
AI summary
An impedance matching method includes: calculating an output impedance of a theoretical circuit model set in advance from actual values of two variable components and a measured value of an input impedance; calculating values of the two variable components at the time of impedance matching through an arithmetic operation under a matching condition in the theoretical circuit model based on the calculated value of the output impedance assuming that the output impedance due to matching transition has the same value; and controlling the actual values of the variable components of the impedance matching device to correspond to the calculated two variable component values.