High-Frequency Power Circuit Phase Control for Plasma Current Distribution
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Solution Overview
Problem
In plasma treatment systems, the impedance changes due to plasma production deviate from theoretical values, causing deviations in current distribution ratios between antenna circuits, even when variable capacitors are set to predetermined values, due to varying conditions such as pressure and gas type.
Innovation Solution
A high-frequency power circuit with series-connected antenna circuits and variable capacitors, where a controller adjusts the capacitance of each variable capacitor based on detected phase differences between current and voltage to maintain resonance and minimize impedance deviations, ensuring the impedance ratio matches theoretical values even during plasma production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If variable capacitors are set to predetermined values to control current distribution ratio, then the theoretical impedance ratio can be determined, but the actual current distribution ratio deviates from theoretical value due to plasma production
Solution Approach 1:
The patent introduces a feedback control mechanism where the controller detects the phase difference between current and voltage in each antenna circuit during plasma production, and dynamically adjusts the capacitance of variable capacitors to minimize this phase difference. This closed-loop feedback system compensates for impedance changes caused by plasma production, ensuring the actual current distribution ratio matches the theoretical value.
Solution Approach 2:
The patent transitions from static capacitor settings to dynamic adjustment. The variable capacitors are no longer fixed at predetermined values but are continuously adjusted based on real-time detection of phase differences. This dynamic adaptation allows the system to maintain optimal current distribution despite changing plasma conditions such as pressure and gas type variations.
2Adaptability or versatility
If capacitance of variable capacitors is changed to adjust current distribution, then plasma density distribution can be controlled, but impedance deviation from theoretical value increases
Solution Approach 1:
The controller uses phase difference detection as feedback to dynamically adjust capacitance values. By continuously monitoring the phase relationship between current and voltage, the system can adapt capacitance settings to maintain both plasma density control and impedance accuracy simultaneously.
Solution Approach 2:
The patent changes the operating parameters of the variable capacitors from fixed predetermined values to dynamically adjusted values based on phase difference detection. This parameter adaptation allows the system to optimize both plasma density distribution and impedance ratio accuracy under varying plasma production conditions.
3Power
If multiple antenna circuits are connected in parallel to the same matching box, then plasma production capability is enhanced, but current distribution ratio deviates from theoretical value due to plasma-induced impedance changes
Solution Approach 1:
The patent implements independent feedback control for each antenna circuit connected in parallel. The controller detects phase differences in each circuit separately and adjusts the corresponding variable capacitor to minimize the phase difference, ensuring that each antenna circuit maintains its theoretical current distribution ratio despite the presence of other plasma-producing circuits.
Solution Approach 2:
The patent applies local control to each antenna circuit by independently adjusting the capacitance of variable capacitors in each circuit based on local phase difference detection. This localized quality adjustment ensures that each antenna circuit maintains optimal current distribution independently, preventing interference and impedance deviations caused by parallel plasma production.
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 configuration minimizes the deviation between actual and theoretical current distribution ratios, allowing for precise control of plasma distribution and stability in plasma treatment processes, while preventing thermal instability in circuit elements.
Implementation Method 1
a controller that sets a capacitance of the first variable capacitor based on a detection result of a phase difference between current and voltage in a series-connected portion of the first antenna and the first variable capacitor during plasma production so as to reduce the phase difference between current and voltage
Implementation Method 2
sets a capacitance of the first variable capacitor based on a detection result of a phase difference between current and voltage in a series-connected portion of the first antenna and the first variable capacitor during plasma production so as to reduce the phase difference between current and voltage
Implementation Method 3
a first antenna for plasma production, a first distribution capacitor located between the first antenna and the matching box
Implementation Method 4
An etching apparatus is an example of a plasma treatment apparatus that uses inductively coupled plasma
Data Source
AI summary
A high-frequency power circuit includes a first antenna circuit and a second antenna circuit that are connected in parallel to a matching box connected to a high-frequency power supply. The first antenna circuit include a first antenna, a first distribution capacitor, and a first variable capacitor. The second antenna circuit includes a second antenna, a second distribution capacitor, and a second variable capacitor. A controller sets a capacitance of the first variable capacitor based on a detection result of a phase difference between current and voltage in a series-connected portion of the first antenna and the first variable capacitor during plasma production to reduce this phase difference and sets a capacitance of the second variable capacitor based on a detection result of a phase difference between current and voltage in a series-connected portion of the second antenna and the second variable capacitor during plasma production to reduce this phase difference.