Plasma Control Apparatus Impedance Matching
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Solution Overview
Problem
Conventional plasma control apparatuses face challenges in achieving high-speed impedance matching between a power source unit and plasma, leading to instability and reduced accuracy in plasma processing due to changes in plasma impedance during processing.
Innovation Solution
The introduction of a resonance producing unit with an LC circuit and a sensor to detect phase differences between current and voltage, allowing for control of radio-frequency power to maintain a resonant state and stabilize voltage and current, even when plasma impedance changes, thereby enabling high-speed impedance matching without mechanical drivers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional impedance matching devices with mechanical drivers are used, then impedance matching can be achieved, but the matching speed is slow and cannot keep up with plasma impedance changes
Solution Approach 1:
The patent replaces mechanical driver-based impedance matching with an electronic control system that uses a sensor to detect plasma impedance changes and a controller to adjust matching network components electronically. This substitution eliminates mechanical movement limitations, enabling high-speed impedance tracking that keeps pace with dynamic plasma conditions, thereby resolving the contradiction between matching speed and processing stability.
2Adaptability or versatility
If plasma impedance changes during processing, then plasma dynamics are maintained, but impedance matching becomes difficult and control accuracy decreases
Solution Approach 1:
The patent implements a feedback control system where a sensor continuously monitors plasma impedance parameters and feeds this information to a controller. The controller dynamically adjusts the impedance matching network to maintain optimal matching conditions despite plasma impedance variations. This closed-loop feedback mechanism enables the system to adapt to changing plasma states while maintaining precise voltage and current control accuracy.
3Productivity
If mechanical drivers are used for impedance matching, then component adjustment is possible, but the system complexity increases and high-speed response is unachievable
Solution Approach 1:
The patent replaces complex mechanical driver systems with an electronic control architecture that uses solid-state components and digital signal processing. This substitution reduces mechanical complexity while enabling high-speed response through electronic adjustment of matching network parameters, thereby improving processing efficiency without excessive system complexity.
Solution Approach 2:
The patent implements a self-adjusting impedance matching system where the sensor and controller automatically detect and compensate for plasma impedance changes without requiring external mechanical intervention. This self-service capability eliminates the need for complex mechanical drivers while maintaining high-speed adaptation, resolving the contradiction between productivity and device complexity.
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 allows for stable and accurate plasma processing by maintaining voltage and current close to set targets, even with changing plasma impedance, enhancing processing stability and accuracy.
Implementation Method 1
a sensor configured to detect a phase difference between current flowing in and voltage applied to the LC circuit
Implementation Method 2
control a frequency of the radio-frequency power to be supplied in such a manner as to minimize the phase difference detected with the sensor
Implementation Method 3
a coil used as the element 10, and in a case where the plasma P is what is called inductively coupled plasma, the radio-frequency power applied to coil 10 by the plasma control apparatus 200′ generates a magnetic field
Implementation Method 4
excites gas with its pressure controlled in the chamber C, generating the plasma P
Data Source
AI summary
A plasma control apparatus includes a power source unit, a resonance producing unit, and a voltmeter. The resonance producing unit includes an LC circuit formed by a coil L1 and a capacitor C1 connected to each other, and a sensor S2 configured to detect a phase difference between current flowing in and voltage applied to the LC circuit, and the capacitor C1 of the LC circuit has a capacitance larger than an expected capacitance of the plasma P. The power source unit 1 configured to control the magnitude of radio-frequency power to be supplied in such a manner as to bring the voltage measured with the voltmeter 5 close to a set voltage as a target, and controls the frequency of the radio-frequency power to be supplied in such a manner as to minimize the phase difference detected with the sensor S2.