High-Frequency Power Supply System Impedance Matching
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Solution Overview
Problem
In high-frequency power supply systems for plasma reactors, the rapid changes in plasma impedance due to low-frequency bias power supply voltage lead to inter-modulation distortion (IMD), resulting in increased reflected wave power, which hampers efficient power delivery to the load.
Innovation Solution
A high-frequency power supply system that includes a bias power supply, a source power supply, and a matching unit with an impedance matching circuit. The source power supply provides a sinusoidal synchronizing signal to the bias power supply, allowing the matching unit to divide the power into sections, perform frequency matching calculations, and adjust the bias power output accordingly to minimize impedance mismatch and reduce IMD.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a dual-frequency power supply is provided with a matching unit using a motor-operated impedance variable element, then impedance matching between source power supply and plasma reactor can be achieved, but the matching operation cannot follow rapid changes in plasma impedance caused by bias power supply voltage variations
Solution Approach 1:
The patent replaces the motor-operated mechanical impedance adjustment system with an electronic impedance variable element that can be controlled by electronic signals. This substitution enables the impedance to change rapidly in response to plasma impedance variations caused by bias power supply voltage changes, eliminating the speed limitation of mechanical motors while maintaining stable impedance matching.
Solution Approach 2:
The patent implements a feedback control mechanism where the system monitors plasma impedance changes and automatically adjusts the electronic impedance variable element to maintain optimal matching. This feedback loop enables real-time adaptation to rapid plasma impedance variations, ensuring both stability and fast response without requiring mechanical motor operation.
2Loss of energy
If impedance matching is performed using a motor-operated variable element in the matching unit, then power supply efficiency can be improved, but inter-modulation distortion increases causing reflected wave power to increase
Solution Approach 1:
By replacing the motor-operated mechanical impedance adjustment with an electronically controlled impedance variable element, the system eliminates the inter-modulation distortion generated by mechanical operation. This substitution reduces harmful electromagnetic interference while maintaining efficient power transfer and minimizing reflected wave power through precise electronic impedance control.
Data Source
AI summary
Proposed are techniques for suppressing an increase in a reflected wave power Pr (synonymous with a reflection coefficient) due to IMD. A high-frequency power supply system for providing a high-frequency power to a connected load includes: a bias power supply that outputs a bias power at a first frequency; a source power supply that outputs a source power at a second frequency higher than the first frequency; and a matching unit including an impedance matching circuit that acquires the bias power and the source power, and provides matching between an impedance on the source power supply side and an impedance on the load side. The source power supply supplies the bias power supply with a sinusoidal synchronizing signal including information about an output frequency to be outputted by the bias power supply, and the bias power supply outputs the bias power of a frequency corresponding to the output frequency included in the sinusoidal synchronizing signal. The matching unit performs a process for dividing a forward wave power due to the source power supply for one cycle of the bias power and a reflected wave power toward the source power supply, into a plurality of sections, a process for performing, with respect to each of the plurality of sections, a frequency matching calculation to determine a frequency setting value for each section, and a process for transmitting the frequency setting value for each section to the source power supply. The source power supply, in accordance with the frequency setting values for the plurality of sections transmitted from the matching unit, outputs the bias power in the plurality of section.