Stacked Planar RF Filter for Plasma Processing
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Solution Overview
Problem
Traditional RF coils for high-power applications face challenges in compactness and repeatability due to frequency-dependent properties of ferromagnetic materials, and larger air-core coils are not feasible in space-constrained systems, necessitating a compact solution that maintains performance across various frequencies.
Innovation Solution
The development of a compact, high-power RF filter using stacked, substantially planar coils without ferromagnetic cores, which provides high impedance to RF frequencies through constructively interfering magnetic paths and adjustable inductance, allowing for effective RF blocking while accommodating spatial constraints and high-power requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If ferromagnetic cores are used in RF coils, then the coil length and volume are reduced, but the performance repeatability deteriorates and production cost increases
Solution Approach 1:
The patent removes ferromagnetic cores from the RF coil design, extracting the problematic component that caused performance variability. The air-core coil eliminates frequency-dependent electrical, magnetic, and thermal properties of ferromagnetic materials, thereby improving performance repeatability while maintaining a compact form factor through optimized coil geometry and stacking arrangements.
Solution Approach 2:
The patent changes the fundamental parameter of the coil core from ferromagnetic material to air, thereby eliminating the frequency-dependent properties that caused performance issues. This parameter change allows the coil to maintain consistent performance across different RF frequencies while still achieving compact dimensions through careful design of the coil windings and stacking configuration.
2Reliability
If air-core coils are used instead of ferromagnetic-core coils, then performance repeatability improves, but the coil size increases significantly
Solution Approach 1:
The patent divides the coil structure into multiple stacked planar segments rather than using a single large coil. This segmentation allows the air-core coil to achieve the required inductance and performance repeatability while maintaining a compact overall volume. The stacked configuration enables space-efficient arrangement that would not be possible with a traditional single-layer air-core coil.
Solution Approach 2:
The patent transitions from a traditional single-plane coil geometry to a three-dimensional stacked planar coil structure. By utilizing the vertical dimension through stacking multiple planar coils, the design achieves the necessary electrical performance of a large air-core coil while confining the physical volume to a compact footprint suitable for modern RF systems.
3Power
If traditional air-core coils are designed to meet high-power requirements, then power handling capability improves, but the physical size increases making them unsuitable for space-constrained systems
Solution Approach 1:
The patent segments the high-power RF coil into multiple stacked planar units, each capable of handling a portion of the total power. This segmentation allows the distribution of thermal and electrical stress across multiple smaller components, enabling high power handling capability while maintaining a compact overall volume that fits within space-constrained system configurations.
Solution Approach 2:
The patent merges multiple planar coil segments into a unified stacked structure that functions as a single high-power RF coil. By combining the electrical and thermal management capabilities of individual segments into an integrated stacked assembly, the design achieves high power handling capability in a compact form factor suitable for modern RF systems with space constraints.
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 solution achieves efficient RF blocking and minimizes electromagnetic compatibility issues and power loss, maintaining performance across a wide range of frequencies within a compact form factor, eliminating the need for ferromagnetic cores and enabling effective convective cooling.
Implementation Method 1
The RF filter presents a high impedance to a source side at the frequencies of interest... constructively interfering magnetic paths
Implementation Method 2
The coil windings can be directly coupled to the cooling channels with high efficiency... enabling effective convective cooling
Data Source
AI summary
Various embodiments include an apparatus to filter radio-frequencies in a plasma-based processing device. In various embodiments, an RF filter device includes a number of substantially-planar spiral-filters electrically coupled to and substantially parallel to each other in a spaced-apart arrangement. In one embodiment, each of the planar spiral-filters is coupled to an adjacent one of the planar spiral filters as either an inside-to-inside electrical connection or an outside-to-outside electrical connection based on an arrangement of the successive spirals so as to increase a total value of inductance. Other methods, devices, apparatuses, and systems are disclosed.