Inductively Coupled RF Plasma Source With Magnetic Confinement
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Solution Overview
Problem
Inductively coupled RF plasma sources face a trade-off between magnetic confinement for higher plasma density and Faraday shielding to suppress parasitic capacitive components, with internal antenna configurations providing better confinement but no Faraday shielding, and external configurations allowing shielding but not effective confinement.
Innovation Solution
An inductively coupled RF plasma system that combines magnetic confinement using a multi-cusp magnet array embedded within a dielectric window and Faraday shielding by orienting the antenna array perpendicular to the magnetization vector, allowing both effective plasma confinement and suppression of parasitic capacitive coupling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If an internal antenna configuration is used, then magnetic confinement is improved for higher plasma density, but Faraday shielding is lost allowing parasitic capacitive components
Solution Approach 1:
The antenna system is segmented into multiple parallel antenna elements that can be independently controlled. This segmentation allows the system to create specific electromagnetic field patterns that enhance magnetic confinement while suppressing parasitic capacitive coupling through constructive and destructive interference of the electromagnetic fields from different antenna elements.
Solution Approach 2:
The system changes the operational parameters by using perpendicular orientation between the antenna array and magnetization vector, and by operating at specific RF frequencies and power levels. This parameter optimization enables the antenna to generate the desired electromagnetic fields for plasma generation while the perpendicular geometry suppresses parasitic capacitive effects, resolving the contradiction between plasma density and parasitic suppression.
2Object-generated harmful factors
If an external antenna configuration is used, then Faraday shielding is achieved to suppress parasitic capacitive components, but magnetic confinement is reduced lowering plasma density
Solution Approach 1:
The invention transitions from traditional single-dimension antenna placement to a two-dimensional array configuration where multiple antenna elements are arranged in parallel. The antenna array is positioned in a plane perpendicular to the magnetization vector of the external magnets. This dimensional change allows the system to achieve both Faraday shielding benefits from external positioning and effective magnetic confinement through the collective field pattern of the antenna array.
Solution Approach 2:
The system merges the benefits of external antenna positioning (Faraday shielding) with effective magnetic confinement by combining multiple antenna elements into an array that operates in coordination with the external magnet array. The perpendicular orientation of the antenna array relative to the magnetization vector allows both functions to coexist, merging previously mutually exclusive advantages.
3Power
If traditional plasma generation is used, then plasma is generated but plasma losses to chamber walls occur reducing efficiency
Solution Approach 1:
The system applies preliminary magnetic confinement through the external magnet array before plasma losses can occur to the chamber walls. The magnetic field is pre-established in the chamber volume, creating magnetic mirrors and cusps that guide and confine plasma particles away from the walls before they can be lost, thereby improving overall plasma generation efficiency and reducing wall losses.
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 achieves higher plasma density and uniformity while reducing plasma losses and parasitic capacitive components, enabling operation at lower neutral gas pressures and improved ion implantation uniformity.
Implementation Method 1
Inductively coupled RF plasma sources... plasma electrons are accelerated in a direction parallel to a current carrying antenna by an electric field resulting from an induced magnetic field according to the Maxwell-Faraday equation
Implementation Method 2
magnetic confinement to the inner surface of the plasma chamber to reduce plasma losses to the walls
Implementation Method 3
Faraday shielding to suppress parasitic capacitive components... inserting a Faraday shield between the antenna and the plasma
Implementation Method 4
plasma chamber comprised of walls and a dielectric window having an inner and outer surface wherein the inner surface seals the volume of the plasma chamber
Data Source
AI summary
Disclosed is an inductively coupled RF plasma source that provides both magnetic confinement to reduce plasma losses and Faraday shielding to suppress parasitic capacitive components. The inductively coupled RF plasma system comprises an RF power source, plasma chamber, an array of permanent magnets, and an antenna array. The plasma chamber is comprised of walls and a dielectric window having an inner and outer surface wherein the inner surface seals the volume of the plasma chamber. The array of parallel conductive permanent magnets is electrically interconnected and embedded within the dielectric window walls proximate to the inner surface and coupled to ground on one end. The permanent magnet array elements are alternately magnetized toward and away from plasma in the plasma chamber to form a multi-cusp magnetic field. The antenna array may be comprised of parallel tubes through which an RF current is circulated. The antenna array is oriented perpendicular to the permanent magnet array.