Impedance Matching Network with Segmented Capacitor Switching
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Solution Overview
Problem
Existing impedance matching networks in plasma applications face challenges in efficiently handling high voltages and achieving a wide range of impedance matches with minimal component count and space usage, particularly in semiconductor manufacturing, where variable capacitors often require large or multiple components to manage voltage and current effectively.
Innovation Solution
The implementation of a variable capacitor network comprising coarse and fine capacitors in parallel, with a control circuit to gradually increase total capacitance by switching in capacitors in a predetermined order, and the use of a heat pipe inductor for improved cooling in high-power systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If traditional variable capacitors are used to achieve wide impedance matching range, then the impedance matching capability is improved, but the component count and space usage increase
Solution Approach 1:
The variable capacitor is segmented into multiple discrete capacitor elements with specific capacitance values. These segments can be individually switched in or out of the circuit to achieve different total capacitance values, enabling wide impedance matching range without requiring a single large variable capacitor component
Solution Approach 2:
The capacitor network dynamically reconfigures its total capacitance by switching individual capacitor elements in and out of the circuit based on the required impedance matching conditions. This dynamic adjustment allows the system to adapt to varying plasma load impedances while maintaining a compact fixed structure
2Reliability
If multiple capacitors are used to handle high voltages, then the voltage handling capability is improved, but the space requirement increases
Solution Approach 1:
Multiple capacitor elements are merged into a single parallel network configuration. When multiple capacitors are connected in parallel, their voltage ratings combine to handle higher voltages while occupying less space than individual capacitors would require if used separately
Solution Approach 2:
The capacitor network serves multiple functions simultaneously: it provides voltage handling capability through parallel configuration, enables impedance matching through selective switching, and maintains compact size through integrated design. Each capacitor element contributes to both voltage distribution and total capacitance adjustment
3Adaptability or versatility
If more capacitors and switches are added to expand impedance range, then the adaptability is improved, but the device complexity and space usage worsen
Solution Approach 1:
The capacitor bank is segmented into discrete elements with specifically chosen capacitance values that enable comprehensive impedance coverage. This segmentation allows the system to achieve wide impedance matching range using fewer total components compared to using many small equal-value capacitors
Solution Approach 2:
The system changes the total capacitance parameter by switching between discrete capacitor configurations. By selecting from pre-determined capacitor value combinations, the system achieves continuous-like impedance adjustment across a wide range without requiring physically continuous variable capacitors
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
This solution enhances the ability to handle high voltages, reduces the need for large or multiple components, and provides efficient cooling, thereby increasing the usable range of impedance matches and maintaining impedance range without adding more components or space, while effectively managing power dissipation in semiconductor manufacturing.
Implementation Method 1
the use of a heat pipe inductor for improved cooling in high-power systems
Data Source
AI summary
In one embodiment, an RF impedance matching network for a plasma chamber is disclosed. It includes a variable capacitor comprising a plurality of capacitors comprising first coarse capacitors each having a substantially similar first coarse capacitance, second coarse capacitors each having a substantially similar second coarse capacitance, and fine capacitors having different capacitances that increase in value. At least one of the fine capacitors has a capacitance greater than the first coarse capacitance. A control circuit is configured cause a gradual increase in the total capacitance of the variable capacitor by switching in, in a predetermined order, each of the first coarse capacitors, followed by each of the second coarse capacitors, only switching in the fine capacitors whose capacitance is less than a capacitance of a next coarse capacitor of the coarse capacitors predetermined to be switched in next.