Dielectric Window Resonators for Cutoff-Limited Plasma Processing
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Solution Overview
Problem
In plasma processing apparatuses using microwaves for plasma excitation, increasing microwave power leads to a cutoff density where the permittivity becomes negative, preventing microwaves from propagating and limiting the generation of high-density plasma over a wide range.
Innovation Solution
The plasma processing apparatus incorporates a dielectric window with a resonator array structure, where C-shaped ring members made of conductors are inserted into grooves on the dielectric, allowing the microwaves to resonate with magnetic field components and maintain negative permeability, enabling microwaves to propagate beyond the skin depth and be efficiently absorbed by plasma, even at cutoff density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If microwave power is increased to generate high-density plasma, then plasma density is improved, but permittivity becomes negative causing microwave propagation to be blocked
Solution Approach 1:
The patent changes the electromagnetic parameters of the dielectric window by incorporating resonators that can adjust the effective permeability. By tuning the resonator parameters (size, shape, arrangement), the effective permeability can be made negative at specific microwave frequencies, allowing propagation even when plasma density is high and permittivity is negative.
Solution Approach 2:
The dielectric window is constructed as a composite material combining dielectric substrate with metallic resonators (C-shaped or ring structures). This composite structure creates effective medium properties where the resonators contribute negative permeability while the dielectric provides positive permittivity, enabling microwave propagation through high-density plasma regions.
2Volume of moving object
If dielectric window size is reduced to miniaturize processing chamber, then volume is improved, but plasma generation capability may be compromised
Solution Approach 1:
The dielectric window is segmented into multiple resonator units (C-shaped or ring structures) arranged in arrays. Each resonator acts as an independent element contributing to the overall negative permeability effect. This segmentation allows the window to maintain electromagnetic functionality while reducing overall size and enabling integration into compact processing chambers.
Solution Approach 2:
The resonators are arranged in two-dimensional arrays on the dielectric window surface, utilizing planar space efficiently. This dimensional arrangement allows the compact window structure to achieve the required effective medium properties through collective resonator behavior, maintaining plasma generation capability in a reduced volume.
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 the generation of high-density plasma over a wide range by ensuring microwaves can propagate and be absorbed, overcoming the limitations of cutoff density, and also miniaturizes the processing chamber while controlling plasma spread.
Implementation Method 1
the resonators are capable of resonating with magnetic field components of the electromagnetic waves
Implementation Method 2
enabling microwaves to propagate beyond the skin depth and be efficiently absorbed by plasma
Implementation Method 3
allowing the microwaves to resonate with magnetic field components and maintain negative permeability, enabling microwaves to propagate beyond the skin depth
Implementation Method 4
an electromagnetic wave generator configured to generate electromagnetic waves for plasma excitation supplied to the processing space
Data Source
AI summary
There is a plasma processing apparatus comprising: a processing chamber configured to provide a processing space; an electromagnetic wave generator configured to generate electromagnetic waves for plasma excitation supplied to the processing space; a dielectric provided with a first surface facing the processing space; and an electromagnetic wave supply portion configured to supply the electromagnetic waves to the processing space through the dielectric, wherein the dielectric includes: a cell serving as a plasma generation space on the first surface side, a plurality of grooves formed on a second surface opposite to the first surface, the grooves surrounding the cell without communicating with the cell; and resonators including C-shaped ring members made of conductors inserted into the plurality of grooves, wherein the resonators are capable of resonating with magnetic field components of the electromagnetic waves and have a size smaller than a wavelength of the electromagnetic wave.