Coaxial Waveguide Plasma Source with Linear Magnetic Circuit
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Solution Overview
Problem
Existing plasma sources for surface treatments face challenges in achieving uniformity and directing plasma effectively towards substrates, leading to energy losses and contamination issues due to their magnetic configurations and sensitivity to conductive deposits.
Innovation Solution
A plasma source with a linear magnetic circuit surrounding coaxial waveguides, featuring a magnetic trap and optimized antenna designs to maintain RCE conditions and reduce plasma losses, including a concentric disk and elongated plate antennas to ensure efficient energy transfer and minimize contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If multiple dipolar RCE sources are juxtaposed to create extended plasma, then the plasma extent along an axis is improved, but the uniformity of deposition deteriorates and plasma losses towards walls increase
Solution Approach 1:
The plasma source is divided into multiple independent RCE sources arranged in an array, each contributing to the overall plasma extent. This segmentation allows the plasma to be extended along the axis while maintaining control over each individual source's plasma flow direction, thereby improving both plasma extent and deposition uniformity.
Solution Approach 2:
The invention transitions from simple linear juxtaposition of dipolar sources to a multi-dimensional magnetic field configuration. By introducing magnetic fields with specific orientations in multiple dimensions, the plasma flow is directed more effectively towards the substrate, reducing wall losses and improving deposition uniformity across the extended plasma region.
2Length of stationary object
If dipolar RCE sources are used to extend plasma, then the plasma extent is improved, but plasma losses towards walls increase due to inability to direct plasma towards substrates
Solution Approach 1:
The magnetic field configuration is designed to be dynamic in nature, with fields that can be adjusted to optimize plasma direction. The magnetic fields are configured to actively guide plasma flow towards the substrate plane, creating a more controlled and directed plasma transport that reduces losses to the chamber walls while maintaining extended plasma extent.
3Reliability
If hollow waveguide structures are used to contain plasma, then plasma confinement is improved, but sensitivity to conductive deposits increases and plasma flow directionality deteriorates
Solution Approach 1:
The invention extracts the plasma confinement function from the waveguide structure itself and implements it through dedicated magnetic field configurations. By separating the microwave transmission function (waveguide) from the plasma confinement function (magnetic fields), the system eliminates the sensitivity to conductive deposits on waveguide surfaces while maintaining effective plasma confinement and improving plasma directionality towards the substrate.
4Area of stationary object
If multiple RCE sources are placed side by side to exceed single source width, then processing width is improved, but plasma density uniformity deteriorates due to magnetic interaction between sources
Solution Approach 1:
Each RCE source in the array is equipped with its own optimized magnetic field configuration tailored to its specific position in the array. This local optimization ensures that each source maintains its plasma density and flow characteristics independently, preventing the magnetic interactions that would otherwise cause uniformity deterioration. The magnetic fields are configured locally to direct plasma from each source effectively towards the substrate.
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 provides a plasma source with improved uniformity and reduced energy losses, maintaining plasma intensity along its length and minimizing contamination risks, enhancing treatment efficiency and speed.
Implementation Method 1
electronic cyclotron resonance takes place when an electromagnetic wave and a static magnetic field are applied at the same time strong enough so that the frequency of the cyclotron movement of the electrons around the magnetic field lines is equal to the frequency of the wave. Thus the electrons can absorb the energy of the wave and then transmit it to the gas to form a plasma.
Implementation Method 2
a magnetic circuit elongated in one direction, said magnetic circuit surrounding the guides wave by creating a magnetic field capable of achieving an RCE condition near said waveguides
Implementation Method 3
at least two coaxial waveguides consisting of a central conductor and an external conductor for bringing microwaves into a treatment chamber
Data Source
Figure 1~2
Figure 3~4
Figure 5A~6
AI summary
The device comprises at least two coaxial wave guides (4), each consisting of a central conductor (1) and an external conductor (2) to supply microwaves to a treatment chamber, characterised in that at least the two electromagnetic wave injection guides (4) are combined with a magnetic circuit (21-22) extended in one direction, said magnetic circuit surrounding the wave guides (4), creating a magnetic field capable of creating an ECR condition near said wave guides.