Plasma Confinement Rings and Dielectric Shielding for Arc Prevention
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Solution Overview
Problem
Plasma un-confinement events occur due to high-impedance gaps and sharp edges in RF chamber components, leading to arcing and unintended plasma ignition outside the intended plasma sustaining region, causing damage to hardware and instability in substrate processing.
Innovation Solution
The implementation of dielectric shielding structures, such as sleeves and corner-draping covers, to shield gaps and sharp components from surrounding gas spaces, combined with adjusting the spacing between confinement rings to ensure the gap between rings is greater than the worst-case Debye length, thereby reducing the occurrence of plasma un-confinement events.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If gaps exist between mating surfaces of RF chamber components, then assembly and manufacturing are easier, but high-impedance obstacles form causing arcing and plasma un-confinement events
Solution Approach 1:
A conductive transition piece is introduced as an intermediary component between adjacent RF chamber components. This transition piece bridges the gap between mating surfaces, providing a continuous conductive path for RF current and eliminating high-impedance obstacles that would otherwise cause arcing and plasma un-confinement events.
Solution Approach 2:
The conductive transition piece is designed as a simple, easily replaceable component that can be manufactured at low cost. If arcing occurs or maintenance is needed, the transition piece can be quickly replaced without requiring complex repairs or chamber disassembly, minimizing downtime and maintaining reliability.
2Ease of manufacture
If sharp edges are present on RF chamber components, then manufacturing is simpler, but charged particles are ejected into surrounding gas spaces causing unwanted plasma ignition
Solution Approach 1:
Rounded edges and corners are provided on RF chamber components instead of sharp edges. This curvature prevents electric field concentration at sharp points, thereby preventing charged particle ejection and unwanted plasma ignition in surrounding gas spaces while maintaining ease of manufacture through standard machining practices.
3Adaptability or versatility
If RF current traverses multiple interfaces between chamber components, then chamber design is more flexible, but voltage builds up across gaps leading to arcing
Solution Approach 1:
Conductive transition pieces serve as intermediary components at each interface where RF current passes between chamber components. These transition pieces maintain electrical continuity across interfaces, preventing voltage buildup and arcing while allowing the chamber design to remain flexible and modular.
4Productivity
If plasma is generated in unintended gas spaces, then processing stability deteriorates, but substrate processing functionality remains required
Solution Approach 1:
The design converts potentially harmful sharp edges and gaps into beneficial features by rounding edges to prevent arcing and using conductive transition pieces to manage current flow. This eliminates plasma un-confinement events while maintaining stable plasma generation in the intended region for effective substrate processing.
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 significantly reduces and prevents plasma un-confinement events by shielding charged particles and improving plasma confinement, leading to a more stable and controlled plasma processing environment.
Implementation Method 1
a dielectric shielding structure configured to shield at least a portion of the gap from surrounding gas spaces in the plasma processing chamber during the processing
Implementation Method 2
adjusting the spacing between confinement rings to ensure the gap between rings is greater than the worst-case Debye length
Data Source
AI summary
A method for configuring a plasma processing chamber for preventing a plasma un-confinement event during processing of a substrate from occurring outside of a confined plasma sustaining region is provided. The confined plasma sustaining region is defined by a set of confinement rings surrounding a bottom portion of an electrode is provided. The method includes determining a worst-case Debye length for a plasma generated in the plasma processing chamber during the processing. The method also includes performing at least one of adjusting gaps between any pair of adjacent confinement rings and adding at least one additional confinement ring to ensure that a gap between the any pair of adjacent confinement rings is less than the worst-case Debye length.