Ferrite Transformer RF Source for Plasma Uniformity
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Solution Overview
Problem
Conventional plasma processing apparatuses generate metals within the chamber due to high-energy ions bombarding the dielectric window, resulting in an unwanted electrical field during inductively coupled RF plasmas, which is not ideal for uniform plasma creation.
Innovation Solution
A RF source using a ferrite material with an insulated wire coil creates a magnetic field without a significant electrical field, either by positioning it on a dielectric window or extending the magnetic field into the chamber, to induce plasma formation without the capacitive electrical field.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If an inductively coupled RF plasma source is used to generate plasma, then plasma generation is achieved, but an unwanted electrical field is created due to high-energy ions bombarding the dielectric window
Solution Approach 1:
The patent extracts the harmful capacitive electrical field component from the plasma generation process by using a transformer-coupled RF source that generates only a magnetic field. The primary coil generates a magnetic field that induces a current in the secondary coil within the plasma chamber, creating plasma without the unwanted electrical field that would otherwise be generated by conventional inductive coupling methods.
Solution Approach 2:
The patent introduces a transformer as an intermediary device between the RF power source and the plasma chamber. The transformer couples the RF power to the plasma indirectly through magnetic field induction, avoiding direct electrical field interaction with the dielectric window and eliminating the generation of unwanted electrical fields and metal contamination.
2Quantity of substance
If conventional RF antennas are used to generate plasma, then plasma is created, but metal generation within the chamber occurs due to ion bombardment
Solution Approach 1:
The patent removes the mechanism that causes metal generation (electrical field and ion bombardment of dielectric window) while preserving plasma generation. By using transformer-coupled magnetic field induction instead of conventional RF antenna methods, the harmful ion bombardment and subsequent metal generation are eliminated.
Solution Approach 2:
The patent replaces the conventional RF antenna system with a transformer-coupled magnetic field induction system. This substitution changes the fundamental mechanism from direct electrical field interaction to magnetic field induction, thereby eliminating the harmful effects of ion bombardment and metal generation while maintaining plasma generation capability.
3Manufacturing precision
If a magnetic field is used to create plasma without electrical field, then plasma uniformity is enhanced, but device complexity increases due to transformer coupling
Solution Approach 1:
The transformer-coupled RF source performs multiple functions: it provides RF power coupling, generates the magnetic field for plasma generation, and simultaneously eliminates the unwanted electrical field. This multi-functionality justifies the added complexity by delivering multiple benefits in a single integrated system.
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 approach allows for the inductive creation of plasma with reduced electrical field interference, enhancing plasma uniformity and reducing metal generation within the chamber, suitable for use in PLAD chambers and beam line ion implantation systems.
Implementation Method 1
A RF source using a ferrite material with an insulated wire coil creates a magnetic field without a significant electrical field
Implementation Method 2
to induce plasma formation without the capacitive electrical field
Data Source
AI summary
A RF source and method are disclosed which inductively create a plasma within an enclosure without an electric field or with a significantly decreased creation of an electric field. A ferrite material with an insulated wire wrapped around its body is used to efficiently channel the magnetic field through the legs of the ferrite. This magnetic field, which flows between the legs of the ferrite can then be used to create and maintain a plasma. In one embodiment, these legs rest on a dielectric window, such that the magnetic field passes into the chamber. In another embodiment, the legs of the ferrite extend into the processing chamber, thereby further extending the magnetic field into the chamber. This ferrite can be used in conjunction with a PLAD chamber, or an ion source for a traditional beam line ion implantation system.