Capacitively Coupled Remote Plasma Source for Low Power Operation
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Solution Overview
Problem
Existing remote plasma sources face challenges in operating at low power and high pressure, require high current thresholds for optimal performance, and suffer from electrode erosion and non-uniform field distribution, leading to shortened lifetimes and damage to processing materials.
Innovation Solution
A capacitively coupled remote plasma source design featuring a chamber with two electrodes and dielectric components that allow for RF power coupling to sustain plasma, enabling operation at higher frequencies and reducing ion bombardment, with curved edges for uniform field distribution and floating plasma potential to minimize chamber wall damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If inductive coupling is used to sustain plasma, then plasma generation efficiency is improved, but the source requires high current thresholds and cannot operate at low power
Solution Approach 1:
The patent changes the fundamental operating parameters by switching from inductive to capacitive coupling, enabling the plasma source to operate at low power levels while maintaining stable plasma generation. This parameter change allows operation below the critical threshold that limits inductive sources, providing access to low power/high pressure regimes previously unavailable.
2Quantity of substance
If high current density is applied to achieve optimal plasma state, then plasma density is improved, but electrode erosion and chamber wall damage increase
Solution Approach 1:
The patent introduces a capacitive coupling mechanism as an intermediary between the power source and plasma, using electric field coupling through dielectric barriers to sustain plasma without direct high current contact. This intermediary approach maintains high plasma density while eliminating the direct electrode erosion and ion bombardment issues associated with inductive coupling.
3Power
If inductive coils are used to generate plasma, then plasma activation is improved, but non-uniform field distribution causes localized erosion and shortened lifetime
Solution Approach 1:
The patent employs curved electrode geometries with rounded edges and surfaces to distribute the electric field uniformly across the plasma generation region. This curvature design eliminates field concentration at sharp edges and corners, preventing localized hot spots and erosion, thereby extending source lifetime while maintaining effective plasma activation.
4Object-affected harmful factors
If dielectric breaks are incorporated to prevent current flow through chamber body, then electrical safety is improved, but high voltage drop causes ion acceleration and wall erosion
Solution Approach 1:
The patent extracts and eliminates the need for dielectric breaks by redesigning the current path architecture. The capacitive coupling system naturally directs current through the plasma without requiring interruptions in the chamber body, thereby removing the source of high voltage drops and associated ion acceleration that cause wall erosion at dielectric break locations.
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 allows for longer operational lifetimes, reduced ion bombardment, and improved uniformity in field distribution, enabling efficient plasma generation and processing at lower power with reduced chamber damage and extended usage.
Implementation Method 1
The RF power source can be configured to couple to an RF power source input and provide RF power from the RF power source to the first electrode. The RF power can electrostatically couple to the second electrode so as to electrostatically sustain a plasma within at least a portion of the chamber.
Implementation Method 2
Remote plasma sources (RPS) are used to produce activated gases containing ions, free radicals, atoms and molecules by passing a gas through a plasma that excites the gas.
Data Source
AI summary
This disclosure describes systems, methods, and apparatus for capacitively coupling energy into a plasma to ignite and sustain the plasma within a remote plasma source. The power is provided by a first electrode that at least partially surrounds or is surrounded by a second electrode. The second electrode can be grounded or floating. First and second dielectric components can be arranged to separate one or both of the electrodes from the plasma and thereby DC isolate the plasma from one or both of the electrodes.