ICP Coil and Faraday Shield Layout for Stable Plasma Coupling
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Solution Overview
Problem
Inductively coupled plasma (ICP) sources face challenges with plasma instabilities due to sudden changes in impedance when switching between E-mode and H-mode plasmas, leading to inefficiencies and instability in the plasma-coil and power supply coupling circuit.
Innovation Solution
The apparatus includes a remote field power generator coupled to a coil and a shield member with specific configurations, such as radial spokes and slots, to reduce parasitic losses and instabilities. The coil arrangement with inner and outer coils and the shield's design function as a Faraday shield to enhance control over the RF field and plasma formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the system switches between E-mode and H-mode plasma to achieve different plasma densities, then plasma density control is improved, but plasma instability increases due to impedance changes
Solution Approach 1:
A matching network is introduced as an intermediary component between the power source and the plasma coil. This matching network includes variable capacitors and inductors that act as mediators to adjust and match the impedance between the power source and the plasma load, thereby reducing plasma instability during mode transitions while maintaining the ability to control plasma density.
Solution Approach 2:
The matching network employs dynamically adjustable capacitors and inductors that can be tuned in real-time. This dynamic adjustment allows the system to adapt the impedance matching conditions as plasma transitions between E-mode and H-mode, maintaining stability throughout the transition process while preserving plasma density control versatility.
2Ease of operation
If capacitive coupling is used for plasma ignition and low power operation, then ease of plasma initiation is improved, but power transfer efficiency deteriorates
Solution Approach 1:
The system employs periodic switching between capacitive and inductive coupling modes. During the ignition phase, capacitive coupling is activated to easily initiate plasma. Once plasma is established, the system transitions to inductive coupling for efficient power transfer. This periodic action allows the system to capitalize on the advantages of both coupling methods at different operational stages.
Solution Approach 2:
Capacitive coupling is used as a preliminary action to ignite the plasma before transitioning to inductive coupling. This preliminary capacitive coupling phase prepares the plasma for subsequent efficient inductive heating, ensuring easy ignition while minimizing overall energy loss by limiting capacitive coupling to only the necessary ignition period.
3Adaptability or versatility
If sudden impedance changes occur during plasma mode transitions, then plasma mode flexibility is improved, but power delivery stability deteriorates
Solution Approach 1:
The matching network incorporates feedback mechanisms through variable capacitors and inductors that respond to changes in plasma impedance. When plasma transitions between modes causing impedance changes, the feedback system automatically adjusts the matching network components to maintain optimal power transfer, thereby stabilizing power delivery while preserving plasma mode flexibility.
Solution Approach 2:
The system dynamically changes electrical parameters (capacitance and inductance values) in the matching network in response to plasma mode transitions. By adjusting these parameters, the system compensates for impedance changes during mode transitions, maintaining stable power delivery while allowing flexible switching between plasma modes.
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 reduces parasitic power losses and enhances plasma uniformity by minimizing impedance variations, thereby stabilizing the plasma and improving the efficiency of the ICP process.
Implementation Method 1
the electric field is created by an A.C. current, for example R.F., flowing through one or more coils disposed outside of the processing chamber thereby inducing a current in the gas within the adjacent chamber gas volume
Implementation Method 2
The coil may be configured to include an inner coil and an outer coil where in the inner coil and outer coil each have a substantially horizontal portion
Data Source
AI summary
Disclosed herein is an apparatus for processing a substrate using an inductively coupled plasma source. An inductively coupled plasma source utilizes a power source, a shield member, and a coil coupled to the power source. In certain embodiments, the coils are arranged with a horizontal spiral grouping and a vertical extending helical grouping. The shield member, according to certain embodiments, utilizes a grounding member to function as a Faraday shield. The embodiments herein reduce parasitic losses and instabilities in the plasma created by the inductively coupled plasma in the substrate processing system.