Resonating Structure Tuning for High-Density Plasma Microwave Propagation
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Solution Overview
Problem
Existing plasma processing technologies face challenges in stably increasing plasma density beyond a certain cutoff density, as the dielectric constant of the processing chamber becomes negative, preventing microwaves from propagating and being efficiently absorbed by the plasma.
Innovation Solution
A plasma processing apparatus is designed with a resonating structure formed by arranging multiple resonators capable of resonating with the magnetic field component of microwaves. This apparatus measures the resonance frequency of the resonating structure before plasma processing, ensuring accurate resonance and maintaining negative dielectric and magnetic permeability, allowing microwaves to propagate beyond the skin depth of the plasma.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If microwave power is increased to increase plasma density, then plasma density increases, but when electron density reaches cutoff density the dielectric constant becomes negative and microwaves cannot propagate
Solution Approach 1:
The patent changes the electromagnetic parameters of the processing chamber by introducing a resonating structure that creates negative magnetic permeability. This parameter change allows the chamber to support electromagnetic wave propagation even when the plasma density reaches cutoff conditions, thereby resolving the contradiction between high plasma density and microwave propagation stability
Solution Approach 2:
The patent creates a composite electromagnetic environment by combining the plasma medium with a resonating structure that exhibits negative magnetic permeability. This composite system enables microwave propagation through high-density plasma that would otherwise block wave transmission, solving the propagation stability issue while maintaining high plasma density
2Reliability
If resonating structure is added to enable negative magnetic permeability, then microwave propagation beyond skin depth is enabled, but device complexity increases
Solution Approach 1:
The resonating structure is segmented into multiple discrete resonators arranged in a periodic pattern within the processing chamber. This segmentation allows the negative magnetic permeability effect to be achieved through a modular structure rather than a monolithic complex component, reducing overall device complexity while maintaining propagation reliability
Solution Approach 2:
The resonating structure acts as an intermediary element between the microwave source and the plasma. By placing this intermediate structure in the electromagnetic path, it mediates the interaction between microwaves and plasma, enabling propagation through high-density regions without requiring direct modification of the plasma or the microwave source
3Loss of energy
If resonance frequency measurement is performed before plasma processing, then accurate resonance and efficient microwave absorption are achieved, but measurement time and process complexity increase
Solution Approach 1:
The resonance frequency measurement is performed as a preliminary action before plasma processing begins. This advance measurement ensures that the microwave frequency is optimized for resonance with the processing chamber, guaranteeing efficient energy absorption during the actual processing without requiring time-consuming adjustments during operation
Solution Approach 2:
The measurement system provides feedback about the resonating structure's characteristics, allowing the microwave source frequency to be adjusted to match the resonance frequency. This feedback mechanism ensures optimal microwave absorption efficiency while the measurement is performed only once before processing, minimizing time loss
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 enables the stable increase of plasma density over a wide range by ensuring efficient microwave absorption, even when the electron density reaches the cutoff density, thereby maintaining high-density plasma generation.
Implementation Method 1
a resonating structure disposed in the processing chamber and formed by arranging a plurality of resonators that are capable of resonating with a magnetic field component of the electromagnetic waves
Implementation Method 2
a measurement part configured to measure, for each frequency, a power of the electromagnetic waves traveling from the electromagnetic wave generator to the resonating structure and a power of transmitted waves, reflected waves, or scattered waves of the electromagnetic waves in the resonating structure
Implementation Method 3
enables the stable increase of plasma density over a wide range by ensuring efficient microwave absorption, even when the electron density reaches the cutoff density
Data Source
AI summary
A plasma processing apparatus comprising: a processing chamber; an electromagnetic wave generator; a resonating structure formed by arranging resonators that are capable of resonating with a magnetic field component of electromagnetic waves; a measurement part configured to measure, for each frequency, a power of the electromagnetic waves traveling from the electromagnetic wave generator to the resonating structure and a power of transmitted waves, reflected waves, or scattered waves of the electromagnetic waves in the resonating structure; and a controller that performs measuring the power of the electromagnetic waves and the power of the transmitted waves, the reflected waves, or the scattered waves with the measurement part, and calculating a resonance frequency of the resonating structure based on frequency distribution of characteristic values of the resonating structure, calculated from the power of the electromagnetic waves and the power of the transmitted waves, the reflected waves, or the scattered waves.