ICP Excitation Antenna Layout for Uniform Magnetic Field
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Solution Overview
Problem
Existing antennas for inductively coupled plasma excitation suffer from non-uniform magnetic field strength and reduced generation efficiency due to biased current distribution and dielectric electromotive forces caused by central gas injector openings and branch line configurations.
Innovation Solution
The antenna design incorporates a conductive plate and coil assemblies connected via impedance adjusting parts, with the conductive plate preventing magnetic force line inflow and ensuring uniform current distribution across coil assemblies, improving magnetic field uniformity and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a central coil turn and outer coil turn are connected by radial or arc conductors, then plasma can be generated in the processing chamber, but the current distribution becomes biased and the magnetic field strength uniformity deteriorates
Solution Approach 1:
The antenna is divided into multiple independent coil turns (first coil turn, second coil turn, third coil turn, etc.) arranged concentrically. Each coil turn is electrically isolated and can be independently controlled, eliminating the current distribution bias that occurs in connected coil structures. This segmentation allows each coil to generate magnetic field contributions that collectively achieve uniform plasma generation across the processing chamber.
Solution Approach 2:
Different coil turns are assigned different impedance values through individually adjustable impedance adjusting parts (capacitors). This allows each local region of the antenna to have optimized electrical characteristics, enabling precise control over current distribution and magnetic field generation at different radial positions, thereby achieving overall magnetic field uniformity.
2Device complexity
If RF power is supplied to the central coil turn and the outer coil turn is grounded, then the antenna structure is simplified, but the circumferential uniformity of magnetic field strength is reduced
Solution Approach 1:
The antenna structure is segmented into multiple independently controllable coil turns rather than using a single connected structure. Each coil turn can be independently biased and controlled, allowing the system to achieve uniform magnetic field distribution without relying on a complex interconnected structure with centralized power supply and grounding.
Solution Approach 2:
The impedance of each coil turn is independently adjustable through impedance adjusting parts (capacitors). By changing the electrical parameters (impedance, capacitance) of each coil individually, the system can optimize current distribution to achieve uniform magnetic field strength circumferentially, while maintaining structural simplicity through modular coil design.
3Productivity
If branch lines are used to distribute current to multiple coils, then the antenna can excite plasma, but dielectric electromotive forces are generated and magnetic field generation efficiency is reduced
Solution Approach 1:
Instead of using branch lines to distribute current from a central source, the antenna employs multiple independently powered coil turns. Each coil receives RF power directly through its own impedance adjusting part, eliminating the need for current distribution through branch lines and the associated dielectric electromotive force losses.
Solution Approach 2:
The problematic branch line structure and central power distribution system are completely removed from the design. Each coil turn is extracted as an independent unit with its own power supply path through the impedance adjusting part, eliminating the source of dielectric electromotive forces and improving magnetic field generation efficiency.
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 design enhances the circumferential uniformity of the magnetic field strength and improves the generation efficiency of the magnetic field, preventing dielectric electromotive forces and reducing bias in current distribution.
Implementation Method 1
antenna for inductively coupled plasma excitation
Implementation Method 2
an impedance adjusting part disposed between the other end of each of the plurality of coil assemblies and the ground
Data Source
AI summary
The present disclosure relates to an antenna for inductively coupled plasma excitation. The antenna comprises: a conductive plate; a plurality of coil assemblies, one end of each of the plurality of coil assemblies being connected to the conductive plate; and an impedance adjusting part disposed between the other end of each of the plurality of coil assemblies and the ground.