Filter Unit for Plasma Processing Noise Attenuation
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Solution Overview
Problem
Conventional plasma processing apparatuses face challenges in effectively filtering out high frequency noises from multiple frequencies, leading to inefficient power consumption and design complexities due to the size and resistance issues of air core coils, and the difficulty in adjusting multiple resonance frequencies for effective noise attenuation.
Innovation Solution
The implementation of a filter unit with an air core coil and a toroidal coil in series, along with condensers, to provide a high impedance and efficiently block high frequency noises of different frequencies entering the power feeding line, allowing for independent adjustment of resonance frequencies and compact design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If an air core coil is used to filter high frequency noises, then the filter can block noise effectively, but the coil size increases and resistance increases leading to power loss
Solution Approach 1:
The patent places the air core coil inside the toroidal coil, creating a nested configuration where the air core coil is positioned within the magnetic field region of the toroidal coil. This nesting allows the air core coil to benefit from the magnetic field of the toroidal coil, enhancing its filtering capability while reducing the required size and resistance of the air core coil itself, thereby reducing power loss.
Solution Approach 2:
The patent combines two different coil structures (air core coil and toroidal coil) with different magnetic properties into a composite filter system. The air core coil provides high frequency noise filtering while the toroidal coil with its ferromagnetic core provides low frequency noise filtering. This composite approach allows each coil to be optimized for its specific frequency range, reducing the overall size and power consumption compared to using a single large air core coil for all frequencies.
2Adaptability or versatility
If multiple high frequency waves are applied to improve plasma process controllability, then plasma generation and ion drawing-in are enhanced, but multiple frequencies of noise enter the heater power feeding line simultaneously
Solution Approach 1:
The patent divides the noise filtering function into two separate frequency-specific filtering stages: the air core coil handles high frequency noise (e.g., 27 MHz plasma generation frequency) while the toroidal coil handles low frequency noise (e.g., 13 MHz ion drawing-in frequency). This segmentation allows each filtering element to be optimized for its target frequency range, effectively addressing the multi-frequency noise problem caused by dual-frequency plasma processing.
Solution Approach 2:
The patent applies different filtering characteristics to different frequency ranges by using two distinct coil configurations with different magnetic properties. The air core coil provides high impedance at high frequencies, while the toroidal coil with ferromagnetic core provides high impedance at low frequencies. This local quality approach ensures that each frequency component of the noise is attenuated by the most suitable filtering mechanism.
3Object-affected harmful factors
If a single air core coil is used to filter multiple frequencies, then the filter design becomes complex and adjustment of multiple resonance frequencies becomes difficult
Solution Approach 1:
The patent segments the multi-frequency filtering task into two separate single-frequency filtering tasks, each handled by a dedicated coil structure. The air core coil is designed and adjusted for high frequency filtering, while the toroidal coil is designed and adjusted for low frequency filtering. This segmentation simplifies the design process, as each coil can be independently optimized and adjusted without affecting the other frequency range.
Solution Approach 2:
The patent merges two independently optimized filtering systems (air core coil for high frequency, toroidal coil for low frequency) into a single integrated filter unit. This combination achieves multi-frequency noise attenuation while maintaining the simplicity of individual coil designs and adjustments, avoiding the complexity that would arise from attempting to design a single coil structure to handle multiple frequencies simultaneously.
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 ensures stable and reliable noise attenuation across multiple frequencies, improving the reproducibility and reliability of the plasma processing by minimizing power loss and simplifying the design and layout of the power supply systems.
Implementation Method 1
the air core coil has a self-resonance frequency near to the first frequency
Implementation Method 2
the toroidal coil has a self-resonance frequency near to the second frequency
Implementation Method 3
the first condenser functions to be capable of obtaining a first series resonance frequency between the first frequency and the second frequency
Implementation Method 4
the second condenser functions to be capable of obtaining a second series resonance frequency lower than the second frequency
Implementation Method 5
This configuration ensures stable and reliable noise attenuation across multiple frequencies, improving the reproducibility and reliability of the plasma processing by minimizing power loss
Data Source
AI summary
Provided is a plasma processing apparatus in which an external circuit is electrically connected, via a line, to a predetermined electric member within a processing container thereof, and noises of first and second high frequency waves are attenuated or blocked by a filter provided on the line when the noises enter the line from the electric member toward the external circuit. The filter includes: an air core coil provided at a first stage when viewed from the electric member side; a toroidal coil connected in series with the air core coil; an electroconductive casing configured to accommodate or enclose the air core coil and the toroidal coil; a first condenser electrically connected between a connection point between the air core coil and the toroidal coil and the casing; and a second condenser connected between a terminal of the toroidal coil at the external circuit side and the casing.