Microwave Automatic Matcher for Plasma Stability
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Solution Overview
Problem
Conventional microwave plasma processing apparatuses suffer from instability and reproducibility issues due to mode jumps in plasma emission, leading to abrupt changes in electron density and repeated fluctuations in plasma intensity, which are not effectively addressed by existing automatic matchers.
Innovation Solution
A microwave automatic matcher is introduced, featuring a movable body within the waveguide, a driving unit, a matching control unit, a reflection coefficient measuring unit, and a setting unit to set and maintain a target reflection coefficient, ensuring impedance matching and stabilizing plasma generation by controlling the movable body to maintain the reflection coefficient within a specified range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional automatic matchers (stub tuner, E tuner, EH tuner) are used for impedance matching in microwave plasma processing apparatus, then impedance matching between microwave generator and load is achieved, but plasma emission instability and hunting phenomenon occur due to mode jumps in plasma density
Solution Approach 1:
The patent implements dynamic control of the movable short-circuit body position based on real-time detection of plasma emission intensity. The controller continuously adjusts the short-circuit body position to maintain optimal impedance matching, transforming the static matcher into a dynamic system that adapts to plasma mode jumps and prevents hunting phenomenon
Solution Approach 2:
The patent introduces a feedback mechanism where plasma emission intensity is detected and used to control the position of the movable short-circuit body. This closed-loop feedback system enables the automatic matcher to respond to plasma condition changes and maintain stable operation by continuously adjusting the matching network
2Productivity
If microwave power is increased to improve plasma density, then plasma generation efficiency is improved, but plasma emission becomes unstable with repeated intensity fluctuations
Solution Approach 1:
The patent changes the control parameter from fixed impedance matching to dynamic impedance matching based on plasma emission intensity. By continuously adjusting the electrical parameters of the automatic matcher according to plasma conditions, the system maintains stable plasma generation even at high power levels, preventing the hunting phenomenon that causes intensity fluctuations
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
The solution effectively prevents hunting of plasma emission, enhancing the stability, reproducibility, and quality of the plasma process by maintaining consistent plasma conditions, thereby improving the uniformity and yield of plasma processing.
Implementation Method 1
a reflection coefficient measuring unit configured to obtain a measurement of a reflection coefficient by detecting a standing wave of microwave propagating through the waveguide
Implementation Method 2
The microwave automatic matcher is capable of improving a matching function to improve stability of plasma generated by a microwave discharge
Data Source
AI summary
A microwave automatic matcher includes a movable body, a driving unit, a matching control unit, a reflection coefficient measuring unit, and a setting unit. The matching control unit consecutively moves the movable body from a start position in one direction by a distance of a difference between the start position and the target position in a matching operation carried out for the plasma process and then variably controls the position of the movable body until the measurement of the reflection coefficient obtained by the reflection coefficient measuring unit falls within the first neighboring range by monitoring the measurement of the reflection coefficient.